Monday, May 18, 2009

The foreign exchange market (currency, forex, or FX) is where currency trading takes place. It is where banks and other official institutions facilitate the buying and selling of foreign currencies. [1]FX transactions typically involve one party purchasing a quantity of one currency in exchange for paying a quantity of another. The foreign exchange market that we see today started evolving during the 1970s when worldover countries gradually switched to floating exchange rate from their erstwhile exchange rate regime, which remained fixed as per the Bretton Woods system till 1971.

Presently, the FX market is one of the largest and most liquid financial markets in the world, and includes trading between large banks, central banks, currency speculators, corporations, governments, and other institutions. The average daily volume in the global foreign exchange and related markets is continuously growing. Traditional daily turnover was reported to be over US$3.2 trillion in April 2007 by the Bank for International Settlements.[2] Since then, the market has continued to grow. According to Euromoney's annual FX Poll, volumes grew a further 41% between 2007 and 2008.[3]

The purpose of FX market is to facilitate trade and investment. The need for a foreign exchange market arises because of the presence of multifarious international currencies such as US Dollar, Pound Sterling, etc., and the need for trading in such currencies.

Contents
1 Market size and liquidity
2 Market participants
2.1 Banks
2.2 Commercial companies
2.3 Central banks
2.4 Hedge funds as speculators
2.5 Investment management firms
2.6 Retail foreign exchange brokers
2.7 Non-bank Foreign Exchange Companies
2.8 Money Transfer/Remittance Companies
3 Trading characteristics
4 Determinants of FX Rates
4.1 Economic factors
4.2 Political conditions
4.3 Market psychology
5 Algorithmic trading in foreign exchange
6 Financial instruments
6.1 Spot
6.2 Forward
6.3 Future
6.4 Swap
6.5 Option
6.6 Exchange-Traded Fund
7 Speculation
8 References
9 See also
10 External links



Market size and liquidity
The foreign exchange market is unique because of

its trading volumes,
the extreme liquidity of the market,
its geographical dispersion,
its long trading hours: 24 hours a day except on weekends (from 22:00 UTC on Sunday until 22:00 UTC Friday),
the variety of factors that affect exchange rates.
the low margins of profit compared with other markets of fixed income (but profits can be high due to very large trading volumes)
the use of leverage

Main foreign exchange market turnover, 1988 - 2007, measured in billions of USD.As such, it has been referred to as the market closest to the ideal perfect competition, notwithstanding market manipulation by central banks. According to the Bank for International Settlements,[2] average daily turnover in global foreign exchange markets is estimated at $3.98 trillion. Trading in the world's main financial markets accounted for $3.21 trillion of this. This approximately $3.21 trillion in main foreign exchange market turnover was broken down as follows:

$1.005 trillion in spot transactions
$362 billion in outright forwards
$1.714 trillion in foreign exchange swaps
$129 billion estimated gaps in reporting
Of the $3.98 trillion daily global turnover, trading in London accounted for around $1.36 trillion, or 34.1% of the total, making London by far the global center for foreign exchange. In second and third places respectively, trading in New York accounted for 16.6%, and Tokyo accounted for 6.0%.[4] In addition to "traditional" turnover, $2.1 trillion was traded in derivatives.

Exchange-traded FX futures contracts were introduced in 1972 at the Chicago Mercantile Exchange and are actively traded relative to most other futures contracts.

Several other developed countries also permit the trading of FX derivative products (like currency futures and options on currency futures) on their exchanges. All these developed countries already have fully convertible capital accounts. Most emerging countries do not permit FX derivative products on their exchanges in view of prevalent controls on the capital accounts. However, a few select emerging countries (e.g., Korea, South Africa, India—[1]; [2]) have already successfully experimented with the currency futures exchanges, despite having some controls on the capital account.

FX futures volume has grown rapidly in recent years, and accounts for about 7% of the total foreign exchange market volume, according to The Wall Street Journal Europe (5/5/06, p. 20).

Top 10 currency traders [5]
% of overall volume, May 2008 Rank Name Volume
1 Deutsche Bank 21.70%
2 UBS AG 15.80%
3 Barclays Capital 9.12%
4 Citi 7.49%
5 Royal Bank of Scotland 7.30%
6 JPMorgan 4.19%
7 HSBC 4.10%
8 Lehman Brothers 3.58%
9 Goldman Sachs 3.47%
10 Morgan Stanley 2.86%

Foreign exchange trading increased by 38% between April 2005 and April 2006 and has more than doubled since 2001. This is largely due to the growing importance of foreign exchange as an asset class and an increase in fund management assets, particularly of hedge funds and pension funds. The diverse selection of execution venues have made it easier for retail traders to trade in the foreign exchange market. In 2006, retail traders constituted over 2% of the whole FX market volumes with an average daily trade volume of over US$50-60 billion (see retail trading platforms).[6] Because foreign exchange is an OTC market where brokers/dealers negotiate directly with one another, there is no central exchange or clearing house. The biggest geographic trading centre is the UK, primarily London, which according to IFSL estimates has increased its share of global turnover in traditional transactions from 31.3% in April 2004 to 34.1% in April 2007. The ten most active traders account for almost 80% of trading volume, according to the 2008 Euromoney FX survey.[3] These large international banks continually provide the market with both bid (buy) and ask (sell) prices. The bid/ask spread is the difference between the price at which a bank or market maker will sell ("ask", or "offer") and the price at which a market-maker will buy ("bid") from a wholesale customer. This spread is minimal for actively traded pairs of currencies, usually 0–3 pips. For example, the bid/ask quote of EUR/USD might be 1.2200/1.2203 on a retail broker. Minimum trading size for most deals is usually 100,000 units of base currency, which is a standard "lot".


These spreads might not apply to retail customers at banks, which will routinely mark up the difference to say 1.2100/1.2300 for transfers, or say 1.2000/1.2400 for banknotes or travelers' checks. Spot prices at market makers vary, but on EUR/USD are usually no more than 3 pips wide (i.e., 0.0003). Competition is greatly increased with larger transactions, and pip spreads shrink on the major pairs to as little as 1 to 2 pips.

Market participants
Financial markets
Bond market
Fixed income
Corporate bond
Government bond
Municipal bond
Bond valuation
High-yield debt


Stock market
Stock
Preferred stock
Common stock
Registered share
Voting share
Stock exchange


Foreign exchange market


Derivatives market
Credit derivative
Hybrid security
Options
Futures
Forwards
Swaps


Other Markets
Commodity market
Money market
OTC market
Real estate market
Spot market


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Finance series
Financial market
Financial market participants
Corporate finance
Personal finance
Public finance
Banks and Banking
Financial regulation


v • d • e

Unlike a stock market, where all participants have access to the same prices, the foreign exchange market is divided into levels of access. At the top is the inter-bank market, which is made up of the largest investment banking firms. Within the inter-bank market, spreads, which are the difference between the bid and ask prices, are razor sharp and usually unavailable, and not known to players outside the inner circle. The difference between the bid and ask prices widens (from 0-1 pip to 1-2 pips for some currencies such as the EUR). This is due to volume. If a trader can guarantee large numbers of transactions for large amounts, they can demand a smaller difference between the bid and ask price, which is referred to as a better spread. The levels of access that make up the foreign exchange market are determined by the size of the “line” (the amount of money with which they are trading). The top-tier inter-bank market accounts for 53% of all transactions. After that there are usually smaller investment banks, followed by large multi-national corporations (which need to hedge risk and pay employees in different countries), large hedge funds, and even some of the retail FX-metal market makers. According to Galati and Melvin, “Pension funds, insurance companies, mutual funds, and other institutional investors have played an increasingly important role in financial markets in general, and in FX markets in particular, since the early 2000s.” (2004) In addition, he notes, “Hedge funds have grown markedly over the 2001–2004 period in terms of both number and overall size” Central banks also participate in the foreign exchange market to align currencies to their economic needs.


Banks
The interbank market caters for both the majority of commercial turnover and large amounts of speculative trading every day. A large bank may trade billions of dollars daily. Some of this trading is undertaken on behalf of customers, but much is conducted by proprietary desks, trading for the bank's own account.

Until recently, foreign exchange brokers did large amounts of business, facilitating interbank trading and matching anonymous counterparts for small fees. Today, however, much of this business has moved on to more efficient electronic systems. The broker squawk box lets traders listen in on ongoing interbank trading and is heard in most trading rooms, but turnover is noticeably smaller than just a few years ago.


Commercial companies
An important part of this market comes from the financial activities of companies seeking foreign exchange to pay for goods or services. Commercial companies often trade fairly small amounts compared to those of banks or speculators, and their trades often have little short term impact on market rates. Nevertheless, trade flows are an important factor in the long-term direction of a currency's exchange rate. Some multinational companies can have an unpredictable impact when very large positions are covered due to exposures that are not widely known by other market participants.

Central banks
National central banks play an important role in the foreign exchange markets. They try to control the money supply, inflation, and/or interest rates and often have official or unofficial target rates for their currencies. They can use their often substantial foreign exchange reserves to stabilize the market. Milton Friedman argued that the best stabilization strategy would be for central banks to buy when the exchange rate is too low, and to sell when the rate is too high—that is, to trade for a profit based on their more precise information. Nevertheless, the effectiveness of central bank "stabilizing speculation" is doubtful because central banks do not go bankrupt if they make large losses, like other traders would, and there is no convincing evidence that they do make a profit trading.

The mere expectation or rumor of central bank intervention might be enough to stabilize a currency, but aggressive intervention might be used several times each year in countries with a dirty float currency regime. Central banks do not always achieve their objectives. The combined resources of the market can easily overwhelm any central bank.[7] Several scenarios of this nature were seen in the 1992–93 ERM collapse, and in more recent times in Southeast Asia.


Hedge funds as speculators
About 70% to 90% of the foreign exchange transactions are speculative. In other words, the person or institution that bought or sold the currency has no plan to actually take delivery of the currency in the end; rather, they were solely speculating on the movement of that particular currency. Hedge funds have gained a reputation for aggressive currency speculation since 1996. They control billions of dollars of equity and may borrow billions more, and thus may overwhelm intervention by central banks to support almost any currency, if the economic fundamentals are in the hedge funds' favor.


Investment management firms
Investment management firms (who typically manage large accounts on behalf of customers such as pension funds and endowments) use the foreign exchange market to facilitate transactions in foreign securities. For example, an investment manager bearing an international equity portfolio needs to purchase and sell several pairs of foreign currencies to pay for foreign securities purchases.

Some investment management firms also have more speculative specialist currency overlay operations, which manage clients' currency exposures with the aim of generating profits as well as limiting risk. Whilst the number of this type of specialist firms is quite small, many have a large value of assets under management (AUM), and hence can generate large trades.


Retail foreign exchange brokers
There are two types of retail brokers offering the opportunity for speculative trading: retail foreign exchange brokers and market makers. Retail traders (individuals) are a small fraction of this market and may only participate indirectly through brokers or banks. Retail brokers, while largely controlled and regulated by the CFTC and NFA might be subject to foreign exchange scams.[8][9] At present, the NFA and CFTC are imposing stricter requirements, particularly in relation to the amount of Net Capitalization required of its members. As a result many of the smaller, and perhaps questionable brokers are now gone. It is not widely understood that retail brokers and market makers typically trade against their clients and frequently take the other side of their trades. This can often create a potential conflict of interest and give rise to some of the unpleasant experiences some traders have had. A move toward NDD (No Dealing Desk) and STP (Straight Through Processing) has helped to resolve some of these concerns and restore trader confidence, but caution is still advised in ensuring that all is as it is presented.


Non-bank Foreign Exchange Companies
Non-bank foreign exchange companies offer currency exchange and international payments to private individuals and companies. These are also known as foreign exchange brokers but are distinct in that they do not offer speculative trading but currency exchange with payments. I.e., there is usually a physical delivery of currency to a bank account.

It is estimated that in the UK, 14% of currency transfers/payments[10] are made via Foreign Exchange Companies.[11] These companies' selling point is usually that they will offer better exchange rates or cheaper payments than the customer's bank. These companies differ from Money Transfer/Remittance Companies in that they generally offer higher-value services.


Money Transfer/Remittance Companies
Money transfer/remittance companies perform high-volume low-value transfers generally by economic migrants back to their home country. In 2007, the Aite Group estimated that there were $369 billion of remittances (an increase of 8% on the previous year). The four largest markets (India, China, Mexico and the Philippines) receive $95 billion. The largest and best known provider is Western Union with 345,000 agents globally.


Trading characteristics
Most traded currencies[2]
Currency distribution of reported FX market turnover Rank Currency ISO 4217 code
(Symbol) % daily share
(April 2007)
1  United States dollar USD ($) 86.3%
2  Euro EUR (€) 37.0%
3  Japanese yen JPY (¥) 17.0%
4  Pound sterling GBP (£) 15.0%
5  Swiss franc CHF (Fr) 6.8%
6  Australian dollar AUD ($) 6.7%
7  Canadian dollar CAD ($) 4.2%
8-9  Swedish krona SEK (kr) 2.8%
8-9  Hong Kong dollar HKD ($) 2.8%
10  Norwegian krone NOK (kr) 2.2%
11  New Zealand dollar NZD ($) 1.9%
12  Mexican peso MXN ($) 1.3%
13  Singapore dollar SGD ($) 1.2%
14  South Korean won KRW (₩) 1.1%
Other 14.5%
Total 200%

There is no unified or centrally cleared market for the majority of FX trades, and there is very little cross-border regulation. Due to the over-the-counter (OTC) nature of currency markets, there are rather a number of interconnected marketplaces, where different currencies instruments are traded. This implies that there is not a single exchange rate but rather a number of different rates (prices), depending on what bank or market maker is trading, and where it is. In practice the rates are often very close, otherwise they could be exploited by arbitrageurs instantaneously. Due to London's dominance in the market, a particular currency's quoted price is usually the London market price. A joint venture of the Chicago Mercantile Exchange and Reuters, called Fxmarketspace opened in 2007 and aspired but failed to the role of a central market clearing mechanism.

The main trading center is London, but New York, Tokyo, Hong Kong and Singapore are all important centers as well. Banks throughout the world participate. Currency trading happens continuously throughout the day; as the Asian trading session ends, the European session begins, followed by the North American session and then back to the Asian session, excluding weekends.

Fluctuations in exchange rates are usually caused by actual monetary flows as well as by expectations of changes in monetary flows caused by changes in gross domestic product (GDP) growth, inflation (purchasing power parity theory), interest rates (interest rate parity, Domestic Fisher effect, International Fisher effect), budget and trade deficits or surpluses, large cross-border M&A deals and other macroeconomic conditions. Major news is released publicly, often on scheduled dates, so many people have access to the same news at the same time. However, the large banks have an important advantage; they can see their customers' order flow.

Currencies are traded against one another. Each pair of currencies thus constitutes an individual product and is traditionally noted XXX/YYY, where YYY is the ISO 4217 international three-letter code of the currency into which the price of one unit of XXX is expressed (called base currency). For instance, EUR/USD is the price of the euro expressed in US dollars, as in 1 euro = 1.5465 dollar. Out of convention, the first currency in the pair, the base currency, was the stronger currency at the creation of the pair. The second currency, counter currency, was the weaker currency at the creation of the pair.

The factors affecting XXX will affect both XXX/YYY and XXX/ZZZ. This causes positive currency correlation between XXX/YYY and XXX/ZZZ.

On the spot market, according to the BIS study, the most heavily traded products were:

EUR/USD: 27%
USD/JPY: 13%
GBP/USD (also called sterling or cable): 12%
and the US currency was involved in 86.3% of transactions, followed by the euro (37.0%), the yen (17.0%), and sterling (15.0%) (see table). Note that volume percentages should add up to 200%: 100% for all the sellers and 100% for all the buyers.

Trading in the euro has grown considerably since the currency's creation in January 1999, and how long the foreign exchange market will remain dollar-centered is open to debate. Until recently, trading the euro versus a non-European currency ZZZ would have usually involved two trades: EUR/USD and USD/ZZZ. The exception to this is EUR/JPY, which is an established traded currency pair in the interbank spot market. As the dollar's value has eroded during 2008, interest in using the euro as reference currency for prices in commodities (such as oil), as well as a larger component of foreign reserves by banks, has increased dramatically. Transactions in the currencies of commodity-producing countries, such as AUD, NZD, CAD, have also increased.

Determinants of FX Rates
See also: exchange rates
The following theories explain the fluctuations in FX rates in a floating exchange rate regime (In a fixed exchange rate regime, FX rates are decided by its government):

(a) International parity conditions viz; purchasing power parity, interest rate parity, Domestic Fisher effect, International Fisher effect. Though to some extent the above theories provide logical explanation for the fluctuations in exchange rates, yet these theories falter as they are based on challengeable assumptions [e.g., free flow of goods, services and capital] which seldom hold true in the real world.

(b) Balance of payments model (see exchange rate). This model, however, focuses largely on tradable goods and services, ignoring the increasing role of global capital flows. It failed to provide any explanation for continuous appreciation of dollar during 1980s and most part of 1990s in face of soaring US current account deficit.

(c) Asset market model (see exchange rate) views currencies as an important asset class for constructing investment portfolios. Assets prices are influenced mostly by people’s willingness to hold the existing quantities of assets, which in turn depends on their expectations on the future worth of these assets. The asset market model of exchange rate determination states that “the exchange rate between two currencies represents the price that just balances the relative supplies of, and demand for, assets denominated in those currencies.”

None of the models developed so far succeed to explain FX rates levels and volatility in the longer time frames. For shorter time frames (less than a few days) algorithm can be devised to predict prices. Large and small institutions and professional individual traders have made consistent profits from it. It is understood from above models that many macroeconomic factors affect the exchange rates and in the end currency prices are a result of dual forces of demand and supply. The world's currency markets can be viewed as a huge melting pot: in a large and ever-changing mix of current events, supply and demand factors are constantly shifting, and the price of one currency in relation to another shifts accordingly. No other market encompasses (and distills) as much of what is going on in the world at any given time as foreign exchange.

Supply and demand for any given currency, and thus its value, are not influenced by any single element, but rather by several. These elements generally fall into three categories: economic factors, political conditions and market psychology.


Economic factors
These include: (a)economic policy, disseminated by government agencies and central banks, (b)economic conditions, generally revealed through economic reports, and other economic indicators.

1.Economic policy comprises government fiscal policy (budget/spending practices) and monetary policy (the means by which a government's central bank influences the supply and "cost" of money, which is reflected by the level of interest rates).
2.Economic conditions include:
Government budget deficits or surpluses
The market usually reacts negatively to widening government budget deficits, and positively to narrowing budget deficits. The impact is reflected in the value of a country's currency.
Balance of trade levels and trends
The trade flow between countries illustrates the demand for goods and services, which in turn indicates demand for a country's currency to conduct trade. Surpluses and deficits in trade of goods and services reflect the competitiveness of a nation's economy. For example, trade deficits may have a negative impact on a nation's currency.
Inflation levels and trends
Typically a currency will lose value if there is a high level of inflation in the country or if inflation levels are perceived to be rising [. This is because inflation erodes purchasing power, thus demand, for that particular currency. However, a currency may sometimes strengthen when inflation rises because of expectations that the central bank will raise short-term interest rates to combat rising inflation.
Economic growth and health
Reports such as GDP, employment levels, retail sales, capacity utilization and others, detail the levels of a country's economic growth and health. Generally, the more healthy and robust a country's economy, the better its currency will perform, and the more demand for it there will be.
Productivity of an economy
Increasing productivity in an economy should positively influence the value of its currency. It affects are more prominent if the increase is in the traded sector [3].

[edit] Political conditions
Internal, regional, and international political conditions and events can have a profound effect on currency markets.

All exchange rates are susceptible to political instability and anticipations about the new ruling party. Political upheaval and instability can have a negative impact on a nation's economy. For example, destabilization of coalition governments in India, Pakistan and Thailand can negatively affect the value of their currencies. Similarly, in a country experiencing financial difficulties, the rise of a political faction that is perceived to be fiscally responsible can have the opposite effect. Also, events in one country in a region may spur positive or negative interest in a neighboring country and, in the process, affect its currency.


Market psychology
Market psychology and trader perceptions influence the foreign exchange market in a variety of ways:

Flights to quality
Unsettling international events can lead to a "flight to quality," with investors seeking a "safe haven". There will be a greater demand, thus a higher price, for currencies perceived as stronger over their relatively weaker counterparts. The Swiss franc has been a traditional safe haven during times of political or economic uncertainty.[12]
Long-term trends
Currency markets often move in visible long-term trends. Although currencies do not have an annual growing season like physical commodities, business cycles do make themselves felt. Cycle analysis looks at longer-term price trends that may rise from economic or political trends. [13]
"Buy the rumor, sell the fact"
This market truism can apply to many currency situations. It is the tendency for the price of a currency to reflect the impact of a particular action before it occurs and, when the anticipated event comes to pass, react in exactly the opposite direction. This may also be referred to as a market being "oversold" or "overbought".[14] To buy the rumor or sell the fact can also be an example of the cognitive bias known as anchoring, when investors focus too much on the relevance of outside events to currency prices.
Economic numbers
While economic numbers can certainly reflect economic policy, some reports and numbers take on a talisman-like effect: the number itself becomes important to market psychology and may have an immediate impact on short-term market moves. "What to watch" can change over time. In recent years, for example, money supply, employment, trade balance figures and inflation numbers have all taken turns in the spotlight.
Technical trading considerations
As in other markets, the accumulated price movements in a currency pair such as EUR/USD can form apparent patterns that traders may attempt to use. Many traders study price charts in order to identify such patterns.[15]

Algorithmic trading in foreign exchange
Electronic trading is growing in the FX market, and algorithmic trading is becoming much more common. According to financial consultancy Celent estimates, by 2008 up to 25% of all trades by volume will be executed using algorithm, up from about 18% in 2005.[citation needed]

An algorithmic trader needs to be mindful of potential fraud by the broker. Part of the weekly algorithm should include a check to see if the amount of transaction errors when the trader is losing money occurs in the same proportion as when the trader would have made money.


Financial instruments
Spot
A spot transaction is a two-day delivery transaction (except in the case of trades between the US Dollar, Canadian Dollar, Turkish Lira and Russian Ruble, which settle the next business day), as opposed to the futures contracts, which are usually three months. This trade represents a “direct exchange” between two currencies, has the shortest time frame, involves cash rather than a contract; and interest is not included in the agreed-upon transaction. The data for this study come from the spot market. Spot transactions has the second largest turnover by volume after Swap transactions among all FX transactions in the Global FX market. NNM


Forward
See also: forward contract
One way to deal with the foreign exchange risk is to engage in a forward transaction. In this transaction, money does not actually change hands until some agreed upon future date. A buyer and seller agree on an exchange rate for any date in the future, and the transaction occurs on that date, regardless of what the market rates are then. The duration of the trade can be a one day, a few days, months or years. Usually the date is decided by both parties.


Future
Main article: currency future
Foreign currency futures are exchange traded forward transactions with standard contract sizes and maturity dates — for example, $1000 for next November at an agreed rate [4],[5]. Futures are standardized and are usually traded on an exchange created for this purpose. The average contract length is roughly 3 months. Futures contracts are usually inclusive of any interest amounts.

Swap
Main article: foreign exchange swap
The most common type of forward transaction is the currency swap. In a swap, two parties exchange currencies for a certain length of time and agree to reverse the transaction at a later date. These are not standardized contracts and are not traded through an exchange.

Main article: foreign exchange option
A foreign exchange option (commonly shortened to just FX option) is a derivative where the owner has the right but not the obligation to exchange money denominated in one currency into another currency at a pre-agreed exchange rate on a specified date. The FX options market is the deepest, largest and most liquid market for options of any kind in the world.

Exchange-Traded Fund
Main article: exchange-traded fund
Exchange-traded funds (or ETFs) are open ended investment companies that can be traded at any time throughout the course of the day. Typically, ETFs try to replicate a stock market index such as the S&P 500 (e.g., SPY), but recently they are now replicating investments in the currency markets with the ETF increasing in value when the US Dollar weakens versus a specific currency, such as the Euro. Certain of these funds track the price movements of world currencies versus the US Dollar, and increase in value directly counter to the US Dollar, allowing for speculation in the US Dollar for US and US Dollar denominated investors and speculators.


Speculation
Controversy about currency speculators and their effect on currency devaluations and national economies recurs regularly. Nevertheless, economists including Milton Friedman have argued that speculators ultimately are a stabilizing influence on the market and perform the important function of providing a market for hedgers and transferring risk from those people who don't wish to bear it, to those who do.[16] Other economists such as Joseph Stiglitz consider this argument to be based more on politics and a free market philosophy than on economics.[17]

Large hedge funds and other well capitalized "position traders" are the main professional speculators.

Currency speculation is considered a highly suspect activity in many countries. While investment in traditional financial instruments like bonds or stocks often is considered to contribute positively to economic growth by providing capital, currency speculation does not; according to this view, it is simply gambling that often interferes with economic policy. For example, in 1992, currency speculation forced the Central Bank of Sweden to raise interest rates for a few days to 500% per annum, and later to devalue the krona.[18] Former Malaysian Prime Minister Mahathir Mohamad is one well known proponent of this view. He blamed the devaluation of the Malaysian ringgit in 1997 on George Soros and other speculators.

Gregory J. Millman reports on an opposing view, comparing speculators to "vigilantes" who simply help "enforce" international agreements and anticipate the effects of basic economic "laws" in order to profit.[19]

In this view, countries may develop unsustainable financial bubbles or otherwise mishandle their national economies, and foreign exchange speculators allegedly made the inevitable collapse happen sooner. A relatively quick collapse might even be preferable to continued economic mishandling. Mahathir Mohamad and other critics of speculation are viewed as trying to deflect the blame from themselves for having caused the unsustainable economic conditions. Given that Malaysia recovered quickly after imposing currency controls directly against IMF advice, this view is open to doubt.


[edit] References
1.^ Sullivan, arthur; Steven M. Sheffrin (2003). Economics: Principles in action. Upper Saddle River, New Jersey 07458: Pearson Prentice Hall. pp. 551. ISBN 0-13-063085-3. http://www.pearsonschool.com/index.cfm?locator=PSZ3R9&PMDbSiteId=2781&PMDbSolutionId=6724&PMDbCategoryId=&PMDbProgramId=12881&level=4.
2.^ a b c Triennial Central Bank Survey (December 2007), Bank for International Settlements.
3.^ a b Annual FX poll (May 2008), Euromoney.
4.^ BIS Triennial Central Bank Survey, published in December 2007.
5.^ Source: Euromoney FX survey FX Poll 2008: The Euromoney FX survey is the largest global poll of foreign exchange service providers.'
6.^ http://www.ifsl.org.uk/upload/CBS_Foreign_Exchange_2007.pdf (December 2007), International Financial Services, London.
7.^ Alan Greenspan, The Roots of the Mortgage Crisis: Bubbles cannot be safely defused by monetary policy before the speculative fever breaks on its own. , the Wall Street Journal, December 12, 2007
8.^ McKay, Peter A. (2005-07-26). "Scammers Operating on Periphery Of CFTC's Domain Lure Little Guy With Fantastic Promises of Profits". The Wall Street Journal (Dow Jones and Company). http://online.wsj.com/article/SB112233850336095645.html?mod=Markets-Main. Retrieved on 2007-10-31.
9.^ Egan, Jack (2005-06-19). "Check the Currency Risk. Then Multiply by 100". The New York Times. http://www.nytimes.com/2005/06/19/business/yourmoney/19fore.html?_r=2&adxnnl=1&oref=slogin&adxnnlx=1191337503-g1yHfewhqPWye0XtI+Eq0A&oref=slogin. Retrieved on 2007-10-30.
10.^ The Sunday Times (UK), 16 July 2006
11.^ The 5 largest in the UK are Travelex, Moneycorp, HiFX, World First and Currencies Direct
12.^ Safe haven currency
13.^ John J. Murphy, Technical Analysis of the Financial Markets (New York Institute of Finance, 1999), pp. 343–375.
14.^ Investopedia
15.^ Sam Y. Cross, All About the Foreign Exchange Market in the United States, Federal Reserve Bank of New York (1998), chapter 11, pp. 113–115.
16.^ Michael A. S. Guth, "Profitable Destabilizing Speculation," Chapter 1 in Michael A. S. Guth, SPECULATIVE BEHAVIOR AND THE OPERATION OF COMPETITIVE MARKETS UNDER UNCERTAINTY, Avebury Ashgate Publishing, Aldorshot, England (1994), ISBN 1856289850.
17.^ What I Learned at the World Economic Crisis Joseph Stiglitz, The New Republic, April 17, 2000, reprinted at GlobalPolicy.org
18.^ But Don't Rush Out to Buy Kronor: Sweden's 500% Gamble - International Herald Tribune
19.^ Gregory J. Millman, Around the World on a Trillion Dollars a Day, Bantam Press, New York, 1995.



Economics is the social science that studies the production, distribution, and consumption of goods and services. The term economics comes from the Ancient Greek οἰκονομία (oikonomia, "management of a household, administration") from οἶκος (oikos, "house") + νόμος (nomos, "custom" or "law"), hence "rules of the house(hold)".[1] Current economic models developed out of the broader field of political economy in the late 19th century, owing to a desire to use an empirical approach more akin to the physical sciences.[2] A definition that captures much of modern economics is that of Lionel Robbins in a 1932 essay: "the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses."[3] Scarcity means that available resources are insufficient to satisfy all wants and needs. Absent scarcity and alternative uses of available resources, there is no economic problem. The subject thus defined involves the study of choices as they are affected by incentives and resources.

Economics aims to explain how economies work and how economic agents interact. Economic analysis is applied throughout society, in business, finance and government, but also in crime,[4] education,[5] the family, health, law, politics, religion,[6] social institutions, war,[7] and science.[8] The expanding domain of economics in the social sciences has been described as economic imperialism.[9][10] Common distinctions are drawn between various dimensions of economics: between positive economics (describing "what is") and normative economics (advocating "what ought to be") or between economic theory and applied economics or between mainstream economics (more "orthodox" dealing with the "rationality-individualism-equilibrium nexus") and heterodox economics (more "radical" dealing with the "institutions-history-social structure nexus"[11]). However the primary textbook distinction is between microeconomics ("small" economics), which examines the economic behavior of agents (including individuals and firms) and macroeconomics ("big" economics), addressing issues of unemployment, inflation, monetary and fiscal policy for an entire economy.

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This box: view • talk • edit
Contents [hide]
1 History of economic thought
1.1 Classical political economy
1.2 Marxism
1.3 Neoclassical economics
1.4 Keynesian economics
1.5 Chicago School of economics
1.6 Other schools and approaches
2 Microeconomics
2.1 Markets
2.2 Specialization
2.3 Supply and demand
2.4 Market failure
2.5 Firms
2.6 Public sector
3 Macroeconomics
3.1 Growth
3.2 Depression and unemployment
3.3 Inflation and monetary policy
3.4 Fiscal policy and regulation
4 International economics
5 Economics in practice
5.1 Theory
5.2 Empirical investigation
5.3 Game theory
5.4 Profession
6 Economics and other subjects
7 Criticisms of economics
7.1 Criticism of assumptions
8 See also
9 Notes
10 References
11 External links



History of economic thought

The upper part of the stele of Hammurabi's code of lawsMain articles: History of economic thought and Schools of economics
The city states of Sumer developed a trade and market economy based originally on the commodity money of the Shekel which was a certain weight measure of barley, while the Babylonians and their city state neighbors later developed the earliest system of economics using a metric of various commodities, that was fixed in a legal code.[12] The early law codes from Sumer could be considered the first (written) economic formula, and had many attributes still in use in the current price system today... such as codified amounts of money for business deals (interest rates), fines in money for 'wrong doing', inheritance rules, laws concerning how private property is to be taxed or divided, etc.[13][14] For a summary of the laws, see Babylonian law and Ancient economic thought.

Economic thought dates from earlier Mesopotamian, Greek, Roman, Indian, Chinese, Persian and Arab civilizations. Notable writers include Aristotle, Chanakya (also known as Kautilya), Qin Shi Huang, Thomas Aquinas and Ibn Khaldun through to the 14th century. Joseph Schumpeter initially considered the late scholastics of the 14th to 17th centuries as "coming nearer than any other group to being the 'founders' of scientific economics" as to monetary, interest, and value theory within a natural-law perspective.[15] After discovering Ibn Khaldun's Muqaddimah, however, Schumpeter later viewed Ibn Khaldun as being the closest forerunner of modern economics,[16] as many of his economic theories were not known in Europe until relatively modern times.[17] Nonetheless, recent research indicates that the Indian scholar-philosopher Chanakya (c. 340-293 BCE) predates Ibn Khaldun by a millennium and a half as the forerunner of modern economics,[18][19][20][21] and has written more expansively on this subject, particularly on political economy. His magnus opus, the Arthashastra (The Science of Wealth and Welfare),[22] is the genesis of economic concepts that include the opportunity cost, the demand-supply framework, diminishing returns, marginal analysis, public goods, the distinction between the short run and the long run, asymmetric information and the producer surplus.[23] In his capacity as an advisor to the throne of the Maurya Empire of ancient India, he has also advised on the sources and prerequisites of economic growth, obstacles to it and on tax incentives to encourage economic growth.[24]


1638 painting of a French seaport during the heyday of mercantilismTwo other groups, later called 'mercantilists' and 'physiocrats', more directly influenced the subsequent development of the subject. Both groups were associated with the rise of economic nationalism and modern capitalism in Europe. Mercantilism was an economic doctrine that flourished from the 16th to 18th century in a prolific pamphlet literature, whether of merchants or statesmen. It held that a nation's wealth depended on its accumulation of gold and silver. Nations without access to mines could obtain gold and silver from trade only by selling goods abroad and restricting imports other than of gold and silver. The doctrine called for importing cheap raw materials to be used in manufacturing goods, which could be exported, and for state regulation to impose protective tariffs on foreign manufactured goods and prohibit manufacturing in the colonies.[25][26]

Physiocrats, a group of 18th century French thinkers and writers, developed the idea of the economy as a circular flow of income and output. Adam Smith described their system "with all its imperfections" as "perhaps the purest approximation to the truth that has yet been published" on the subject. Physiocrats believed that only agricultural production generated a clear surplus over cost, so that agriculture was the basis of all wealth. Thus, they opposed the mercantilist policy of promoting manufacturing and trade at the expense of agriculture, including import tariffs. Physiocrats advocated replacing administratively costly tax collections with a single tax on income of land owners. Variations on such a land tax were taken up by subsequent economists (including Henry George a century later) as a relatively non-distortionary source of tax revenue. In reaction against copious mercantilist trade regulations, the physiocrats advocated a policy of laissez-faire, which called for minimal government intervention in the economy.[27][28]


Classical political economy
Main article: Classical economics
Publication of Adam Smith's The Wealth of Nations in 1776, has been described as "the effective birth of economics as a separate discipline."[29] The book identified land, labor, and capital as the three factors of production and the major contributors to a nation's wealth.


Adam Smith wrote The Wealth of NationsIn Smith's view, the ideal economy is a self-regulating market system that automatically satisfies the economic needs of the populace. He described the market mechanism as an "invisible hand" that leads all individuals, in pursuit of their own self-interests, to produce the greatest benefit for society as a whole. Smith incorporated some of the Physiocrats' ideas, including laissez-faire, into his own economic theories, but rejected the idea that only agriculture was productive.

In his famous invisible-hand analogy, Smith argued for the seemingly paradoxical notion that competitive markets tended to advance broader social interests, although driven by narrower self-interest. The general approach that Smith helped initiate was called political economy and later classical economics. It included such notables as Thomas Malthus, David Ricardo, and John Stuart Mill writing from about 1770 to 1870.[30]

While Adam Smith emphasized the production of income, David Ricardo focused on the distribution of income among landowners, workers, and capitalists. Ricardo saw an inherent conflict between landowners on the one hand and labor and capital on the other. He posited that the growth of population and capital, pressing against a fixed supply of land, pushes up rents and holds down wages and profits.


Malthus cautioned law makers on the effects of poverty reduction policiesThomas Robert Malthus used the idea of diminishing returns to explain low living standards. Population, he argued, tended to increase geometrically, outstripping the production of food, which increased arithmetically. The force of a rapidly growing population against a limited amount of land meant diminishing returns to labor. The result, he claimed, was chronically low wages, which prevented the standard of living for most of the population from rising above the subsistence level.

Malthus also questioned the automatic tendency of a market economy to produce full employment. He blamed unemployment upon the economy's tendency to limit its spending by saving too much, a theme that lay forgotten until John Maynard Keynes revived it in the 1930s.

Coming at the end of the Classical tradition, John Stuart Mill parted company with the earlier classical economists on the inevitability of the distribution of income produced by the market system. Mill pointed to a distinct difference between the market's two roles: allocation of resources and distribution of income. The market might be efficient in allocating resources but not in distributing income, he wrote, making it necessary for society to intervene.

Value theory was important in classical theory. Smith wrote that the "real price of every thing ... is the toil and trouble of acquiring it" as influenced by its scarcity. Smith maintained that, with rent and profit, other costs besides wages also enter the price of a commodity.[31] Other classical economists presented variations on Smith, termed the 'labour theory of value'. Classical economics focused on the tendency of markets to move to long-run equilibrium.


Marxism
Main article: Marxian economics

The Marxist school of economic thought comes from the work of German economist Karl Marx.Marxist (later, Marxian) economics descends from classical economics. It derives from the work of Karl Marx. The first volume of Marx's major work, Das Kapital, was published in German in 1867. In it, Marx focused on the labour theory of value and what he considered to be the exploitation of labour by capital.[32][33] The labour theory of value held that the value of a thing was determined by the labor that went into its production. This contrasts with the modern understanding that the value of a thing is determined by what one is willing to give up to obtain the thing.


Neoclassical economics
Main article: Neoclassical economics
A body of theory later termed 'neoclassical economics' or 'marginalism' formed from about 1870 to 1910. The term 'economics' was popularized by such neoclassical economists as Alfred Marshall as a concise synonym for 'economic science' and a substitute for the earlier, broader term 'political economy'.[34][35] This corresponded to the influence on the subject of mathematical methods used in the natural sciences.[2] Neoclassical economics systematized supply and demand as joint determinants of price and quantity in market equilibrium, affecting both the allocation of output and the distribution of income. It dispensed with the labour theory of value inherited from classical economics in favor of a marginal utility theory of value on the demand side and a more general theory of costs on the supply side.[36]

In microeconomics, neoclassical economics represents incentives and costs as playing a pervasive role in shaping decision making. An immediate example of this is the consumer theory of individual demand, which isolates how prices (as costs) and income affect quantity demanded. In macroeconomics it is reflected in an early and lasting neoclassical synthesis with Keynesian macroeconomics.[37][38]

Neoclassical economics is occasionally referred as orthodox economics whether by its critics or sympathizers. Modern mainstream economics builds on neoclassical economics but with many refinements that either supplement or generalize earlier analysis, such as econometrics, game theory, analysis of market failure and imperfect competition, and the neoclassical model of economic growth for analyzing long-run variables affecting national income.


Keynesian economics
Main articles: Keynesian economics and Post-Keynesian economics

John Maynard Keynes (above, right), widely considered a towering figure in economics.Keynesian economics derives from John Maynard Keynes, in particular his book The General Theory of Employment, Interest and Money (1936), which ushered in contemporary macroeconomics as a distinct field.[39][40] The book focused on determinants of national income in the short run when prices are relatively inflexible. Keynes attempted to explain in broad theoretical detail why high labour-market unemployment might not be self-correcting due to low "effective demand" and why even price flexibility and monetary policy might be unavailing. Such terms as "revolutionary" have been applied to the book in its impact on economic analysis.[41][42][43]

Keynesian economics has two successors. Post-Keynesian economics also concentrates on macroeconomic rigidities and adjustment processes. Research on micro foundations for their models is represented as based on real-life practices rather than simple optimizing models. It is generally associated with the University of Cambridge and the work of Joan Robinson.[44] New-Keynesian economics is also associated with developments in the Keynesian fashion. Within this group researchers tend to share with other economists the emphasis on models employing micro foundations and optimizing behavior but with a narrower focus on standard Keynesian themes such as price and wage rigidity. These are usually made to be endogenous features of the models, rather than simply assumed as in older Keynesian-style ones.


Chicago School of economics
Main article: Chicago school (economics)
The Chicago School of economics is best known for its free market advocacy and monetarist ideas. According to Milton Friedman and monetarists, market economies are inherently stable if left to themselves and depressions result only from government intervention.[45] Friedman, for example, argued that the Great Depression was result of a contraction of the money supply, controlled by the Federal Reserve, and not by the lack of investment as Keynes had argued. Ben Bernanke, current Chairman of the Federal Reserve, is among the economists today generally accepting Friedman's analysis of the causes of the Great Depression.[46] Milton Friedman effectively took many of the basic principles set forth by Adam Smith and the classical economists and modernized them, in a way. One example of this is his article in the September 1970 issue of The New York Times Magazine, where he claims that the social responsibility of business is “to use its resources and engage in activities designed to increase its profits…(through) open and free competition without deception or fraud.” This is tantamount to Smith’s argument that self interest in turn benefits the whole of society.[47]


Other schools and approaches
Main article: Schools of economics
Other well-known schools or trends of thought referring to a particular style of economics practiced at and disseminated from well-defined groups of academicians that have become known worldwide, include the Austrian School, the Freiburg School, the School of Lausanne and the Stockholm school. Contemporary mainstream economics is sometimes separated into the MIT, or Saltwater, approach, and the Chicago, or Freshwater, approach.

Within macroeconomics there is, in general order of their appearance in the literature; classical economics, Keynesian economics, the neoclassical synthesis, post-Keynesian economics, monetarism, new classical economics, and supply-side economics. Alternative developments include ecological economics, institutional economics, evolutionary economics, dependency theory, structuralist economics, world systems theory, thermoeconomics, econophysics and technocracy.


Microeconomics
Main article: Microeconomics
Microeconomics looks at interactions through individual markets, given scarcity and government regulation. A given market might be for a product, say fresh corn, or the services of a factor of production, say bricklaying. The theory considers aggregates of quantity demanded by buyers and quantity supplied by sellers at each possible price per unit. It weaves these together to describe how the market may reach equilibrium as to price and quantity or respond to market changes over time. This is broadly termed supply and demand analysis. Market structures, such as perfect competition and monopoly, are examined as to implications for behavior and economic efficiency. Analysis of change in a single market often proceeds from the simplifying assumption that behavioral relations in other markets remain unchanged, that is, partial-equilibrium analysis. General-equilibrium theory allows for changes in different markets and aggregates across all markets, including their movements and interactions toward equilibrium.[48][49]


Markets
Main articles: Production-possibility frontier, Opportunity cost, and Production theory basics
In microeconomics, production is the conversion of inputs into outputs. It is an economic process that uses resources to create a commodity that is suitable for exchange. This can include manufacturing, warehousing, shipping, and packaging. Some economists define production broadly as all economic activity other than consumption. They see every commercial activity other than the final purchase as some form of production. Production is a process, and as such it occurs through time and space. Because it is a flow concept, production is measured as a "rate of output per period of time". There are three aspects to production processes, including the quantity of the commodity produced, the form of the good created and the temporal and spatial distribution of the commodity produced. Opportunity cost expresses the idea that for every choice, the true economic cost is the next best opportunity. Choices must be made between desirable yet mutually exclusive actions. It has been described as expressing "the basic relationship between scarcity and choice.".[50] The notion of opportunity cost plays a crucial part in ensuring that scarce resources are used efficiently.[51] Thus, opportunity costs are not restricted to monetary or financial costs: the real cost of output forgone, lost time, pleasure or any other benefit that provides utility should also be considered.

The inputs or resources used in the production process are called factors of production. Possible inputs are typically grouped into six categories. These factors are raw materials, machinery, labour services, capital goods, land, and enterprise. In the short-run, as opposed to the long-run, at least one of these factors of production is fixed. Examples include major pieces of equipment, suitable factory space, and key personnel. A variable factor of production is one whose usage rate can be changed easily. Examples include electrical power consumption, transportation services, and most raw material inputs. In the "long-run", all of these factors of production can be adjusted by management. In the short run, a firm's "scale of operations" determines the maximum number of outputs that can be produced, but in the long run, there are no scale limitations. Long-run and short-run changes play an important part in economic models.

Economic efficiency describes how well a system generates the maximum desired output a with a given set of inputs and available technology. Efficiency is improved if more output is generated without changing inputs, or in other words, the amount of "friction" or "waste" is reduced. Economists look for Pareto efficiency, which is reached when a change cannot make someone better off without making someone else worse off. Economic efficiency is used to refer to a number of related concepts. A system can be called economically efficient if: No one can be made better off without making someone else worse off, more output cannot be obtained without increasing the amount of inputs, and production ensures the lowest possible per unit cost. These definitions of efficiency are not exactly equivalent. However, they are all encompassed by the idea that nothing more can be achieved given the resources available.


Specialization
Main articles: Division of labour, Comparative advantage, and Gains from trade
Specialization is considered key to economic efficiency because different individuals or countries have different comparative advantages. While one country may have an absolute advantage in every area over other countries, it could nonetheless specialize in the area which it has a relative comparative advantage, and thereby gain from trading with countries which have no absolute advantages. For example, a country may specialize in the production of high-tech knowledge products, as developed countries do, and trade with developing nations for goods produced in factories, where labor is cheap and plentiful. According to theory, in this way more total products and utility can be achieved than if countries produced their own high-tech and low-tech products. The theory of comparative advantage is largely the basis for the typical economist's belief in the benefits of free trade. This concept applies to individuals, farms, manufacturers, service providers, and economies. Among each of these production systems, there may be a corresponding division of labour with each worker having a distinct occupation or doing a specialized task as part of the production effort, or correspondingly different types of capital equipment and differentiated land uses.[52][53][54]

Adam Smith's Wealth of Nations (1776) discusses the benefits of the division of labour. Smith noted that an individual should invest a resource, for example, land or labour, so as to earn the highest possible return on it. Consequently, all uses of the resource should yield an equal rate of return (adjusted for the relative riskiness of each enterprise). Otherwise reallocation would result. This idea, wrote George Stigler, is the central proposition of economic theory, and is today called the marginal productivity theory of income distribution. French economist Turgot had made the same point in 1766.[55]

In more general terms, it is theorized that market incentives, including prices of outputs and productive inputs, select the allocation of factors of production by comparative advantage, that is, so that (relatively) low-cost inputs are employed to keep down the opportunity cost of a given type of output. In the process, aggregate output increases as a by product or by design.[56] Such specialization of production creates opportunities for gains from trade whereby resource owners benefit from trade in the sale of one type of output for other, more highly-valued goods. A measure of gains from trade is the increased output (formally, the sum of increased consumer surplus and producer profits) from specialization in production and resulting trade.[57][58][59]


Supply and demand
Main article: Supply and demand

The supply and demand model describes how prices vary as a result of a balance between product availability and demand. The graph depicts an increase (that is, right-shift) in demand from D1 to D2 along with the consequent increase in price and quantity required to reach a new equilibrium point on the supply curve (S).The theory of demand and supply is an organizing principle to explain prices and quantities of goods sold and changes thereof in a market economy. In microeconomic theory, it refers to price and output determination in a perfectly competitive market. This has served as a building block for modeling other market structures and for other theoretical approaches.

For a given market of a commodity, demand shows the quantity that all prospective buyers would be prepared to purchase at each unit price of the good. Demand is often represented using a table or a graph relating price and quantity demanded (see boxed figure). Demand theory describes individual consumers as rationally choosing the most preferred quantity of each good, given income, prices, tastes, etc. A term for this is 'constrained utility maximization' (with income as the constraint on demand). Here, utility refers to the (hypothesized) preference relation for individual consumers. Utility and income are then used to model hypothesized properties about the effect of a price change on the quantity demanded. The law of demand states that, in general, price and quantity demanded in a given market are inversely related. In other words, the higher the price of a product, the less of it people would be able and willing to buy of it (other things unchanged). As the price of a commodity rises, overall purchasing power decreases (the income effect) and consumers move toward relatively less expensive goods (the substitution effect). Other factors can also affect demand; for example an increase in income will shift the demand curve outward relative to the origin, as in the figure.

Supply is the relation between the price of a good and the quantity available for sale from suppliers (such as producers) at that price. Supply is often represented using a table or graph relating price and quantity supplied. Producers are hypothesized to be profit-maximizers, meaning that they attempt to produce the amount of goods that will bring them the highest profit. Supply is typically represented as a directly proportional relation between price and quantity supplied (other things unchanged). In other words, the higher the price at which the good can be sold, the more of it producers will supply. The higher price makes it profitable to increase production. At a price below equilibrium, there is a shortage of quantity supplied compared to quantity demanded. This pulls the price up. At a price above equilibrium, there is a surplus of quantity supplied compared to quantity demanded. This pushes the price down. The model of supply and demand predicts that for given supply and demand curves, price and quantity will stabilize at the price that makes quantity supplied equal to quantity demanded. This is at the intersection of the two curves in the graph above, market equilibrium.

For a given quantity of a good, the price point on the demand curve indicates the value, or marginal utility[60] to consumers for that unit of output. It measures what the consumer would be prepared to pay for the corresponding unit of the good. The price point on the supply curve measures marginal cost, the increase in total cost to the supplier for the corresponding unit of the good. The price in equilibrium is determined by supply and demand. In a perfectly competitive market, supply and demand equate cost and value at equilibrium.[61]

Demand and supply can also be used to model the distribution of income to the factors of production, including labour and capital, through factor markets. In a labour market for example, the quantity of labour employed and the price of labour (the wage rate) are modeled as set by the demand for labour (from business firms etc. for production) and supply of labour (from workers).

Demand and supply are used to explain the behavior of perfectly competitive markets, but their usefulness as a standard of performance extends to any type of market. Demand and supply can also be generalized to explain variables applying to the whole economy, for example, quantity of total output and the general price level, studied in macroeconomics.


Diminishing marginal utility, given quantificationIn supply-and-demand analysis, the price of a good coordinates production and consumption quantities. Price and quantity have been described as the most directly observable characteristics of a good produced for the market.[62] Supply, demand, and market equilibrium are theoretical constructs linking price and quantity. But tracing the effects of factors predicted to change supply and demand—and through them, price and quantity—is a standard exercise in applied microeconomics and macroeconomics. Economic theory can specify under what circumstances price serves as an efficient communication device to regulate quantity.[63] A real-world application might attempt to measure how much variables that increase supply or demand change price and quantity.

Marginalism is the use of marginal concepts within economics. Marginal concepts are associated with a specific change in the quantity used of a good or of a service, as opposed to some notion of the over-all significance of that class of good or service, or of some total quantity thereof. The central concept of marginalism proper is that of marginal utility, but marginalists following the lead of Alfred Marshall were further heavily dependent upon the concept of marginal physical productivity in their explanation of cost; and the neoclassical tradition that emerged from British marginalism generally abandoned the concept of utility and gave marginal rates of substitution a more fundamental rôle in analysis.


Market failure
Main articles: Market failure, Government failure, Information economics, Environmental economics, and Agricultural economics

Pollution can be a simple example of market failure. If costs of production are not borne by producers but are by the environment, accident victims or others, then prices are distorted.The term "market failure" encompasses several problems which may undermine standard economic assumptions. Although economists categorise market failures differently,[64] the following categories emerge in the main texts.[65]

Natural monopoly, or the overlapping concepts of "practical" and "technical" monopoly, involves a failure of competition as a restraint on producers. The problem is described as one where the more of a product is made, the greater the returns are. This means it only makes economic sense to have one producer.

Information asymmetries arise where one party has more or better information than the other. The existence of information asymmetry gives rise to problems such as moral hazard, and adverse selection, studied in contract theory. The economics of information has relevance in many fields, including finance, insurance, contract law, and decision-making under risk and uncertainty.[66]

Incomplete markets is a term used for a situation where buyers and sellers do not know enough about each other's positions to price goods and services properly. Based on George Akerlof's Market for Lemons article, the paradigm example is of a dodgy second hand car market. Customers without the possibility to know for certain whether they are buying a "lemon" will push the average price down below what a good quality second hand car would be. In this way, prices may not reflect true values.

Public goods are goods which are undersupplied in a typical market. The defining features are that people can consume public goods without having to pay for them and that more than one person can consume the good at the same time.

Externalities occur where there are significant social costs or benefits from production or consumption that are not reflected in market prices. For example, air pollution may generate a negative externality, and education may generate a positive externality (less crime, etc.). Governments often tax and otherwise restrict the sale of goods that have negative externalities and subsidize or otherwise promote the purchase of goods that have positive externalities in an effort to correct the price distortions caused by these externalities.[67] Elementary demand-and-supply theory predicts equilibrium but not the speed of adjustment for changes of equilibrium due to a shift in demand or supply.[68] In many areas, some form of price stickiness is postulated to account for quantities, rather than prices, adjusting in the short run to changes on the demand side or the supply side. This includes standard analysis of the business cycle in macroeconomics. Analysis often revolves around causes of such price stickiness and their implications for reaching a hypothesized long-run equilibrium. Examples of such price stickiness in particular markets include wage rates in labour markets and posted prices in markets deviating from perfect competition.

Macroeconomic instability, addressed below, is a prime source of market failure, whereby a general loss of business confidence or external shock can grind production and distribution to a halt, undermining ordinary markets that are otherwise sound.


Environmental Scientist sampling waterSome specialised fields of economics deal in market failure more than others. The economics of the public sector is one example, since where markets fail, some kind of regulatory or government programme is the remedy. Much environmental economics concerns externalities or "public bads". Policy options include regulations that reflect cost-benefit analysis or market solutions that change incentives, such as emission fees or redefinition of property rights.[69][70] Environmental economics is related to ecological economics but there are differences.[71]

Sustainable development portal

Firms
Main articles: Theory of the firm, Industrial organization, Labour economics, Financial economics, Business economics, and Managerial economics

In Virtual Markets, buyer and seller are not present and trade via intermediates and electronic information. Pictured: São Paulo Stock Exchange.One of the assumptions of perfectly competitive markets is that there are many producers, none of whom can influence prices or act independently of market forces. In reality, however, people do not simply trade on markets, they work and produce through firms. The most obvious kinds of firms are corporations, partnerships and trusts. According to Ronald Coase people begin to organise their production in firms when the costs of doing business becomes lower than doing it on the market.[72] Firms combine labour and capital, and can achieve far greater economies of scale (when producing two or more things is cheaper than one thing) than individual market trading.

Labour economics seeks to understand the functioning of the market and dynamics for labour. Labour markets function through the interaction of workers and employers. Labour economics looks at the suppliers of labour services (workers), the demanders of labour services (employers), and attempts to understand the resulting patterns of wages and other labour income and of employment and unemployment, Practical uses include assisting the formulation of full employment of policies.[73]

Industrial organization studies the strategic behavior of firms, the structure of markets and their interactions. The common market structures studied include perfect competition, monopolistic competition, various forms of oligopoly, and monopoly.[74]

Financial economics, often simply referred to as finance, is concerned with the allocation of financial resources in an uncertain (or risky) environment. Thus, its focus is on the operation of financial markets, the pricing of financial instruments, and the financial structure of companies.[75]

Managerial economics applies microeconomic analysis to specific decisions in business firms or other management units. It draws heavily from quantitative methods such as operations research and programming and from statistical methods such as regression analysis in the absence of certainty and perfect knowledge. A unifying theme is the attempt to optimize business decisions, including unit-cost minimization and profit maximization, given the firm's objectives and constraints imposed by technology and market conditions.[76][77]


Public sector
Main articles: Economics of the public sector and Public finance
See also: Welfare economics
Public finance is the field of economics that deals with budgeting the revenues and expenditures of a public sector entity, usually government. The subject addresses such matters as tax incidence (who really pays a particular tax), cost-benefit analysis of government programs, effects on economic efficiency and income distribution of different kinds of spending and taxes, and fiscal politics. The latter, an aspect of public choice theory, models public-sector behavior analogously to microeconomics, involving interactions of self-interested voters, politicians, and bureaucrats.[78]

Much of economics is positive, seeking to describe and predict economic phenomena. Normative economics seeks to identify what is economically good and bad.

Welfare economics is a normative branch of economics that uses microeconomic techniques to simultaneously determine the allocative efficiency within an economy and the income distribution associated with it. It attempts to measure social welfare by examining the economic activities of the individuals that comprise society.[79]


Macroeconomics

A depiction of the circular flow of incomeMain article: Macroeconomics
Macroeconomics examines the economy as a whole to explain broad aggregates and their interactions "top down," that is, using a simplified form of general-equilibrium theory.[80] Such aggregates include national income and output, the unemployment rate, and price inflation and subaggregates like total consumption and investment spending and their components. It also studies effects of monetary policy and fiscal policy. Since at least the 1960s, macroeconomics has been characterized by further integration as to micro-based modeling of sectors, including rationality of players, efficient use of market information, and imperfect competition.[81] This has addressed a long-standing concern about inconsistent developments of the same subject.[82] Macroeconomic analysis also considers factors affecting the long-term level and growth of national income. Such factors include capital accumulation, technological change and labor force growth.[83][84]


Growth

World map showing GDP real growth rates for 2008Main articles: Economic growth and General equilibrium
Growth economics studies factors that explain economic growth – the increase in output per capita of a country over a long period of time. The same factors are used to explain differences in the level of output per capita between countries. Much-studied factors include the rate of investment, population growth, and technological change. These are represented in theoretical and empirical forms (as in the neoclassical growth model) and in growth accounting.[85][86]


Depression and unemployment
See also: Circular flow of income, Aggregate supply, Aggregate demand, Great Depression, and Unemployment
The economics of a depression were the spur for the creation of "macroeconomics" as a separate discipline field of study. During the Great Depression of the 1930s, John Maynard Keynes produced a book entitled The General Theory of Employment, Interest and Money. In it he argued that markets were not self correcting and that if the economy was in a crisis of confidence and downward spiral, it was necessary for government to use spending to stimulate the economy (and the animal spirits of the people to regain confidence) back to good health. It would pay the money back later. Otherwise a general deficit of effective demand would lead to a very long slump. A crisis in confidence could send stock markets plummeting, meaning companies go out of business, meaning more redundancies and fewer people with jobs, meaning people have less money to spend, meaning businesses have fewer customers, meaning more companies go out of business, and so on. The circular flow of income needed an external boost by the state.


Inflation and monetary policy
Main articles: Inflation and Monetary policy
See also: Money, Quantity theory of money, Monetary policy, History of money, and Milton Friedman

A 640 BCE one-third stater electrum coin from Lydia, shown larger. One of the first standardized coins.Money is a means of final payment for goods in most price system economies and the unit of account in which prices are typically stated. It includes currency held by the nonbank public and checkable deposits. It has been described as a social convention, like language, useful to one largely because it is useful to others. As a medium of exchange, money facilitates trade. Its economic function can be contrasted with barter (non-monetary exchange). Given a diverse array of produced goods and specialized producers, barter may entail a hard-to-locate double coincidence of wants as to what is exchanged, say apples and a book. Money can reduce the transaction cost of exchange because of its ready acceptability. Then it is less costly for the seller to accept money in exchange, rather than what the buyer produces.[87]

At the level of an economy, theory and evidence are consistent with a positive relationship running from the total money supply to the nominal value of total output and to the general price level. For this reason, management of the money supply is a key aspect of monetary policy.[88][89]


Fiscal policy and regulation
Main articles: Fiscal policy, Government spending, Regulation, and National accounts
National accounting is a method for summarizing aggregate economic activity of a nation. The national accounts are double-entry accounting systems that provide detailed underlying measures of such information. These include the national income and product accounts (NIPA), which provide estimates for the money value of output and income per year or quarter. NIPA allows for tracking the performance of an economy and its components through business cycles or over longer periods. Price data may permit distinguishing nominal from real amounts, that is, correcting money totals for price changes over time.[90][91] The national accounts also include measurement of the capital stock, wealth of a nation, and international capital flows.[92]


International economics
Main articles: International economics and Economic system
International trade studies determinants of goods-and-services flows across international boundaries. It also concerns the size and distribution of gains from trade. Policy applications include estimating the effects of changing tariff rates and trade quotas. International finance is a macroeconomic field which examines the flow of capital across international borders, and the effects of these movements on exchange rates. Increased trade in goods, services and capital between countries is a major effect of contemporary globalization.[93][94][95]


World map showing GDP (PPP) per capita.The distinct field of development economics examines economic aspects of the development process in relatively low-income countries focussing on structural change, poverty, and economic growth. Approaches in development economics frequently incorporate social and political factors.[96][97]

Economic systems is the branch of economics that studies the methods and institutions by which societies determine the ownership, direction, and allocaton of economic resources. An economic system of a society is the unit of analysis. Among contemporary systems at different ends of the organizational spectrum are socialist systems and capitalist systems, in which most production occurs in respectively state-run and private enterprises. In between are mixed economies. A common element is the interaction of economic and political influences, broadly described as political economy. Comparative economic systems studies the relative performance and behavior of different economies or systems.[98][99]


Economics in practice
Main articles: Mathematical economics, Economic methodology, and Schools of economics
Contemporary mainstream economics, as a formal mathematical modeling field, could also be called mathematical economics.[100] It draws on the tools of calculus, linear algebra, statistics, game theory, and computer science.[101] Professional economists are expected to be familiar with these tools, although all economists specialize, and some specialize in econometrics and mathematical methods while others specialize in less quantitative areas. Heterodox economists place less emphasis upon mathematics, and several important historical economists, including Adam Smith and Joseph Schumpeter, have not been mathematicians. Economic reasoning involves intuition regarding economic concepts, and economists attempt to analyze to the point of discovering unintended consequences.


Theory
Mainstream economic theory relies upon a priori quantitative economic models, which employ a variety of concepts. Theory typically proceeds with an assumption of ceteris paribus, which means holding constant explanatory variables other than the one under consideration. When creating theories, the objective is to find ones which are at least as simple in information requirements, more precise in predictions, and more fruitful in generating additional research than prior theories.[102]

In microeconomics, principal concepts include supply and demand, marginalism, rational choice theory, opportunity cost, budget constraints, utility, and the theory of the firm.[103][104] Early macroeconomic models focused on modeling the relationships between aggregate variables, but as the relationships appeared to change over time macroeconomists were pressured to base their models in microfoundations. The aforementioned microeconomic concepts play a major part in macroeconomic models – for instance, in monetary theory, the quantity theory of money predicts that increases in the money supply increase inflation, and inflation is assumed to be influenced by rational expectations. In development economics, slower growth in developed nations has been sometimes predicted because of the declining marginal returns of investment and capital, and this has been observed in the Four Asian Tigers. Sometimes an economic hypothesis is only qualitative, not quantitative.[105]

Expositions of economic reasoning often use two-dimensional graphs to illustrate theoretical relationships. At a higher level of generality, Paul Samuelson's treatise Foundations of Economic Analysis (1947) used mathematical methods to represent the theory, particularly as to maximizing behavioral relations of agents reaching equilibrium. The book focused on examining the class of statements called operationally meaningful theorems in economics, which are theorems that can conceivably be refuted by empirical data.[106]


Empirical investigation
Main article: Econometrics
Economic theories are sometimes tested empirically, largely through the use of econometrics using economic data.[107] The controlled experiments common to the physical sciences are difficult and uncommon in economics, and instead broad data is observationally studied; this type of testing is typically regarded as less rigorous than controlled experimentation, and the conclusions typically more tentative. Statistical methods such as regression analysis are common. Practitioners use such methods to estimate the size, economic significance, and statistical significance ("signal strength") of the hypothesized relation(s) and to adjust for noise from other variables. By such means, a hypothesis may gain acceptance, although in a probabilistic, rather than certain, sense. Acceptance is dependent upon the falsifiable hypothesis surviving tests. Use of commonly accepted methods need not produce a final conclusion or even a consensus on a particular question, given different tests, data sets, and prior beliefs.

Criticism based on professional standards and non-replicability of results serve as further checks against bias, errors, and over-generalization,[108][104] although much economic research has been accused of being non-replicable, and prestigious journals have been accused of not facilitating replication through the provision of the code and data.[109] Like theories, uses of test statistics are themselves open to critical analysis,[110][111][112] although critical commentary on papers in economics in prestigious journals such as the American Economic Review has declined precipitously in the past 40 years.[113] This has been attributed to journals' incentives to maximize citations in order to rank higher on the Social Science Citation Index (SSCI).[114]

In applied economics, input-output models employing linear programming methods are quite common. Large amounts of data are run through computer programs to analyze the impact of certain policies; IMPLAN is one well-known example.

Experimental economics has promoted the use of scientifically controlled experiments. This has reduced long-noted distinction of economics from natural sciences allowed direct tests of what were previously taken as axioms.[115][116] In some cases these have found that the axioms are not entirely correct; for example, the ultimatum game has revealed that people reject unequal offers. In behavioral economics, psychologists Daniel Kahneman and Amos Tversky have won Nobel Prizes in economics for their empirical discovery of several cognitive biases and


Game theory
From Wikipedia, the free encyclopedia
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For other uses, see Game theory (disambiguation).
Game theory is a branch of applied mathematics that is used in the social sciences (most notably economics), biology, engineering, political science, international relations, computer science, and philosophy. Game theory attempts to mathematically capture behavior in strategic situations, in which an individual's success in making choices depends on the choices of others. While initially developed to analyze competitions in which one individual does better at another's expense (zero sum games), it has been expanded to treat a wide class of interactions, which are classified according to several criteria. Today, "game theory is a sort of umbrella or 'unified field' theory for the rational side of social science, where 'social' is interpreted broadly, to include human as well as non-human players (computers, animals, plants)" (Aumann 1987).

Traditional applications of game theory attempt to find equilibria in these games. In an equilibrium, each player of the game has adopted a strategy that they are unlikely to change. Many equilibrium concepts have been developed (most famously the Nash equilibrium) in an attempt to capture this idea. These equilibrium concepts are motivated differently depending on the field of application, although they often overlap or coincide. This methodology is not without criticism, and debates continue over the appropriateness of particular equilibrium concepts, the appropriateness of equilibria altogether, and the usefulness of mathematical models more generally.

Although some developments occurred before it, the field of game theory came into being with the 1944 book Theory of Games and Economic Behavior by John von Neumann and Oskar Morgenstern. This theory was developed extensively in the 1950s by many scholars. Game theory was later explicitly applied to biology in the 1970s, although similar developments go back at least as far as the 1930s. Game theory has been widely recognized as an important tool in many fields. Eight game theorists have won Nobel prizes in economics, and John Maynard Smith was awarded the Crafoord Prize for his application of game theory to biology.

Contents [hide]
1 Representation of games
1.1 Extensive form
1.2 Normal form
1.3 Characteristic function form
1.4 Partition function form
2 Application and challenges
2.1 Political science
2.2 Economics and business
2.2.1 Descriptive
2.2.2 Prescriptive or normative analysis
2.3 Biology
2.4 Computer science and logic
2.5 Philosophy
3 Types of games
3.1 Cooperative or non-cooperative
3.2 Symmetric and asymmetric
3.3 Zero-sum and non-zero-sum
3.4 Simultaneous and sequential
3.5 Perfect information and imperfect information
3.6 Infinitely long games
3.7 Discrete and continuous games
3.8 One-player and many-player games
3.9 Metagames
4 History
5 See also
6 Notes
7 References
7.1 Textbooks and general references
7.2 Historically important texts
7.3 Other print references
7.4 Websites



[edit] Representation of games
See also: List of games in game theory
The games studied in game theory are well-defined mathematical objects. A game consists of a set of players, a set of moves (or strategies) available to those players, and a specification of payoffs for each combination of strategies. Most cooperative games are presented in the characteristic function form, while the extensive and the normal forms are used to define noncooperative games.


[edit] Extensive form
Main article: Extensive form game

An extensive form gameThe extensive form can be used to formalize games with some important order. Games here are often presented as trees (as pictured to the left). Here each vertex (or node) represents a point of choice for a player. The player is specified by a number listed by the vertex. The lines out of the vertex represent a possible action for that player. The payoffs are specified at the bottom of the tree.

In the game pictured here, there are two players. Player 1 moves first and chooses either F or U. Player 2 sees Player 1's move and then chooses A or R. Suppose that Player 1 chooses U and then Player 2 chooses A, then Player 1 gets 8 and Player 2 gets 2.

The extensive form can also capture simultaneous-move games and games with imperfect information. To represent it, either a dotted line connects different vertices to represent them as being part of the same information set (i.e., the players do not know at which point they are), or a closed line is drawn around them.


[edit] Normal form
Player 2
chooses Left Player 2
chooses Right
Player 1
chooses Up 4, 3 –1, –1
Player 1
chooses Down 0, 0 3, 4
Normal form or payoff matrix of a 2-player, 2-strategy game

Main article: Normal-form game
The normal (or strategic form) game is usually represented by a matrix which shows the players, strategies, and payoffs (see the example to the right). More generally it can be represented by any function that associates a payoff for each player with every possible combination of actions. In the accompanying example there are two players; one chooses the row and the other chooses the column. Each player has two strategies, which are specified by the number of rows and the number of columns. The payoffs are provided in the interior. The first number is the payoff received by the row player (Player 1 in our example); the second is the payoff for the column player (Player 2 in our example). Suppose that Player 1 plays Up and that Player 2 plays Left. Then Player 1 gets a payoff of 4, and Player 2 gets 3.

When a game is presented in normal form, it is presumed that each player acts simultaneously or, at least, without knowing the actions of the other. If players have some information about the choices of other players, the game is usually presented in extensive form.


[edit] Characteristic function form
Main article: Cooperative game
In cooperative games with transferable utility no individual payoffs are given. Instead, the characteristic function determines the payoff of each coalition. The standard assumption is that the empty coalition obtains a payoff of 0.

The origin of this form is to be found in the seminal book of von Neumann and Morgenstern who, when studying coalitional normal form games, assumed that when a coalition C forms, it plays against the complementary coalition () as if they were playing a 2-player game. The equilibrium payoff of C is characteristic. Now there are different models to derive coalitional values from normal form games, but not all games in characteristic function form can be derived from normal form games.

Formally, a characteristic function form game (also known as a TU-game) is given as a pair (N,v), where N denotes a set of players and is a characteristic function.

The characteristic function form has been generalised to games without the assumption of transferable utility.


[edit] Partition function form
The characteristic function form ignores the possible externalities of coalition formation. In the partition function form the payoff of a coalition depends not only on its members, but also on the way the rest of the players are partitioned (Thrall & Lucas 1963).


[edit] Application and challenges
Game theory has been used to study a wide variety of human and animal behaviors. It was initially developed in economics to understand a large collection of economic behaviors, including behaviors of firms, markets, and consumers. The use of game theory in the social sciences has expanded, and game theory has been applied to political, sociological, and psychological behaviors as well.

Game theoretic analysis was initially used to study animal behavior by Ronald Fisher in the 1930s (although even Charles Darwin makes a few informal game theoretic statements). This work predates the name "game theory", but it shares many important features with this field. The developments in economics were later applied to biology largely by John Maynard Smith in his book Evolution and the Theory of Games.

In addition to being used to predict and explain behavior, game theory has also been used to attempt to develop theories of ethical or normative behavior. In economics and philosophy, scholars have applied game theory to help in the understanding of good or proper behavior. Game theoretic arguments of this type can be found as far back as Plato.[1]


[edit] Political science
The application of game theory to political science is focused in the overlapping areas of fair division, political economy, public choice, positive political theory, and social choice theory. In each of these areas, researchers have developed game theoretic models in which the players are often voters, states, special interest groups, and politicians.

For early examples of game theory applied to political science, see the work of Anthony Downs. In his book An Economic Theory of Democracy (Downs 1957), he applies a hotelling firm location model to the political process. In the Downsian model, political candidates commit to ideologies on a one-dimensional policy space. The theorist shows how the political candidates will converge to the ideology preferred by the median voter. For more recent examples, see the books by Steven Brams, George Tsebelis, Gene M. Grossman and Elhanan Helpman, or David Austen-Smith and Jeffrey S. Banks.

A game-theoretic explanation for democratic peace is that public and open debate in democracies send clear and reliable information regarding their intentions to other states. In contrast, it is difficult to know the intentions of nondemocratic leaders, what effect concessions will have, and if promises will be kept. Thus there will be mistrust and unwillingness to make concessions if at least one of the parties in a dispute is a nondemocracy (Levy & Razin 2003).


[edit] Economics and business
Economists have long used game theory to analyze a wide array of economic phenomena, including auctions, bargaining, duopolies, fair division, oligopolies, social network formation, and voting systems. This research usually focuses on particular sets of strategies known as equilibria in games. These "solution concepts" are usually based on what is required by norms of rationality. In non-cooperative games, the most famous of these is the Nash equilibrium. A set of strategies is a Nash equilibrium if each represents a best response to the other strategies. So, if all the players are playing the strategies in a Nash equilibrium, they have no unilateral incentive to deviate, since their strategy is the best they can do given what others are doing.

The payoffs of the game are generally taken to represent the utility of individual players. Often in modeling situations the payoffs represent money, which presumably corresponds to an individual's utility. This assumption, however, can be faulty.

A prototypical paper on game theory in economics begins by presenting a game that is an abstraction of some particular economic situation. One or more solution concepts are chosen, and the author demonstrates which strategy sets in the presented game are equilibria of the appropriate type. Naturally one might wonder to what use should this information be put. Economists and business professors suggest two primary uses.


[edit] Descriptive

A three stage Centipede GameThe first known use is to inform us about how actual human populations behave. Some scholars believe that by finding the equilibria of games they can predict how actual human populations will behave when confronted with situations analogous to the game being studied. This particular view of game theory has come under recent criticism. First, it is criticized because the assumptions made by game theorists are often violated. Game theorists may assume players always act in a way to directly maximize their wins (the Homo economicus model), but in practice, human behavior often deviates from this model. Explanations of this phenomenon are many; irrationality, new models of deliberation, or even different motives (like that of altruism). Game theorists respond by comparing their assumptions to those used in physics. Thus while their assumptions do not always hold, they can treat game theory as a reasonable scientific ideal akin to the models used by physicists. However, additional criticism of this use of game theory has been levied because some experiments have demonstrated that individuals do not play equilibrium strategies. For instance, in the centipede game, guess 2/3 of the average game, and the dictator game, people regularly do not play Nash equilibria. There is an ongoing debate regarding the importance of these experiments.[2]

Alternatively, some authors claim that Nash equilibria do not provide predictions for human populations, but rather provide an explanation for why populations that play Nash equilibria remain in that state. However, the question of how populations reach those points remains open.

Some game theorists have turned to evolutionary game theory in order to resolve these worries. These models presume either no rationality or bounded rationality on the part of players. Despite the name, evolutionary game theory does not necessarily presume natural selection in the biological sense. Evolutionary game theory includes both biological as well as cultural evolution and also models of individual learning (for example, fictitious play dynamics).


[edit] Prescriptive or normative analysis
Cooperate Defect
Cooperate -1, -1 -10, 0
Defect 0, -10 -5, -5
The Prisoner's Dilemma

On the other hand, some scholars see game theory not as a predictive tool for the behavior of human beings, but as a suggestion for how people ought to behave. Since a Nash equilibrium of a game constitutes one's best response to the actions of the other players, playing a strategy that is part of a Nash equilibrium seems appropriate. However, this use for game theory has also come under criticism. First, in some cases it is appropriate to play a non-equilibrium strategy if one expects others to play non-equilibrium strategies as well. For an example, see Guess 2/3 of the average.

Second, the Prisoner's dilemma presents another potential counterexample. In the Prisoner's Dilemma, each player pursuing his own self-interest leads both players to be worse off than had they not pursued their own self-interests.


[edit] Biology
Hawk Dove
Hawk v−c, v−c 2v, 0
Dove 0, 2v v, v
The hawk-dove game

Unlike economics, the payoffs for games in biology are often interpreted as corresponding to fitness. In addition, the focus has been less on equilibria that correspond to a notion of rationality, but rather on ones that would be maintained by evolutionary forces. The best known equilibrium in biology is known as the evolutionarily stable strategy (or ESS), and was first introduced in (Smith & Price 1973). Although its initial motivation did not involve any of the mental requirements of the Nash equilibrium, every ESS is a Nash equilibrium.

In biology, game theory has been used to understand many different phenomena. It was first used to explain the evolution (and stability) of the approximate 1:1 sex ratios. (Fisher 1930) suggested that the 1:1 sex ratios are a result of evolutionary forces acting on individuals who could be seen as trying to maximize their number of grandchildren.

Additionally, biologists have used evolutionary game theory and the ESS to explain the emergence of animal communication (Harper & Maynard Smith 2003). The analysis of signaling games and other communication games has provided some insight into the evolution of communication among animals. For example, the mobbing behavior of many species, in which a large number of prey animals attack a larger predator, seems to be an example of spontaneous emergent organization.

Biologists have used the hawk-dove game (also known as chicken) to analyze fighting behavior and territoriality.

Maynard Smith, in the preface to Evolution and the Theory of Games, writes, "[p]aradoxically, it has turned out that game theory is more readily applied to biology than to the field of economic behaviour for which it was originally designed". Evolutionary game theory has been used to explain many seemingly incongruous phenomena in nature.[3]

One such phenomenon is known as biological altruism. This is a situation in which an organism appears to act in a way that benefits other organisms and is detrimental to itself. This is distinct from traditional notions of altruism because such actions are not conscious, but appear to be evolutionary adaptations to increase overall fitness. Examples can be found in species ranging from vampire bats that regurgitate blood they have obtained from a night’s hunting and give it to group members who have failed to feed, to worker bees that care for the queen bee for their entire lives and never mate, to Vervet monkeys that warn group members of a predator's approach, even when it endangers that individual's chance of survival.[4] All of these actions increase the overall fitness of a group, but occur at a cost to the individual.

Evolutionary game theory explains this altruism with the idea of kin selection. Altruists discriminate between the individuals they help; and favor relatives. Hamilton's rule explains the evolutionary reasoning behind this selection with the equation c

[edit] Computer science and logic
Game theory has come to play an increasingly important role in logic and in computer science. Several logical theories have a basis in game semantics. In addition, computer scientists have used games to model interactive computations. Also, game theory provides a theoretical basis to the field of multi-agent systems.

Separately, game theory has played a role in online algorithms. In particular, the k-server problem, which has in the past been referred to as games with moving costs and request-answer games (Ben David, Borodin & Karp et al. 1994). Yao's principle is a game-theoretic technique for proving lower bounds on the computational complexity of randomized algorithms, and especially of online algorithms.

The field of algorithmic game theory combines computer science concepts of complexity and algorithm design with game theory and economic theory. The emergence of the internet has motivated the development of algorithms for finding equilibria in games, markets, computational auctions, peer-to-peer systems, and security and information markets.[5]


[edit] Philosophy
Stag Hare
Stag 3, 3 0, 2
Hare 2, 0 2, 2
Stag hunt

Game theory has been put to several uses in philosophy. Responding to two papers by W.V.O. Quine (1960, 1967), Lewis (1969) used game theory to develop a philosophical account of convention. In so doing, he provided the first analysis of common knowledge and employed it in analyzing play in coordination games. In addition, he first suggested that one can understand meaning in terms of signaling games. This later suggestion has been pursued by several philosophers since Lewis (Skyrms (1996), Grim, Kokalis, and Alai-Tafti et al. (2004)). Following Lewis (1969) game-theoretic account of conventions, Ullmann Margalit (1977) and Bicchieri (2006) have developed theories of social norms that define them as Nash equilibria that result from transforming a mixed-motive game into a coordination game.[6]

Game theory has also challenged philosophers to think in terms of interactive epistemology: what it means for a collective to have common beliefs or knowledge, and what are the consequences of this knowledge for the social outcomes resulting from agents' interactions. Philosophers who have worked in this area include Bicchieri (1989, 1993),[7] Skyrms (1990),[8] and Stalnaker (1999).[9]

In ethics, some authors have attempted to pursue the project, begun by Thomas Hobbes, of deriving morality from self-interest. Since games like the Prisoner's dilemma present an apparent conflict between morality and self-interest, explaining why cooperation is required by self-interest is an important component of this project. This general strategy is a component of the general social contract view in political philosophy (for examples, see Gauthier (1986) and Kavka (1986).[10]

Other authors have attempted to use evolutionary game theory in order to explain the emergence of human attitudes about morality and corresponding animal behaviors. These authors look at several games including the Prisoner's dilemma, Stag hunt, and the Nash bargaining game as providing an explanation for the emergence of attitudes about morality (see, e.g., Skyrms (1996, 2004) and Sober and Wilson (1999)).

Some assumptions used in some parts of game theory have been challenged in philosophy; psychological egoism states that rationality reduces to self-interest—a claim debated among philosophers. (see Psychological egoism#Criticism)


[edit] Types of games

[edit] Cooperative or non-cooperative
Main articles: Cooperative game and Non-cooperative game
A game is cooperative if the players are able to form binding commitments. For instance the legal system requires them to adhere to their promises. In noncooperative games this is not possible.

Often it is assumed that communication among players is allowed in cooperative games, but not in noncooperative ones. This classification on two binary criteria has been rejected (Harsanyi 1974).

Of the two types of games, noncooperative games are able to model situations to the finest details, producing accurate results. Cooperative games focus on the game at large. Considerable efforts have been made to link the two approaches. The so-called Nash-programme[clarification needed] has already established many of the cooperative solutions as noncooperative equilibria.

Hybrid games contain cooperative and non-cooperative elements. For instance, coalitions of players are formed in a cooperative game, but these play in a non-cooperative fashion.


[edit] Symmetric and asymmetric
E F
E 1, 2 0, 0
F 0, 0 1, 2
An asymmetric game

Main article: Symmetric game
A symmetric game is a game where the payoffs for playing a particular strategy depend only on the other strategies employed, not on who is playing them. If the identities of the players can be changed without changing the payoff to the strategies, then a game is symmetric. Many of the commonly studied 2×2 games are symmetric. The standard representations of chicken, the prisoner's dilemma, and the stag hunt are all symmetric games. Some scholars would consider certain asymmetric games as examples of these games as well. However, the most common payoffs for each of these games are symmetric.

Most commonly studied asymmetric games are games where there are not identical strategy sets for both players. For instance, the ultimatum game and similarly the dictator game have different strategies for each player. It is possible, however, for a game to have identical strategies for both players, yet be asymmetric. For example, the game pictured to the right is asymmetric despite having identical strategy sets for both players.


[edit] Zero-sum and non-zero-sum
A B
A –1, 1 3, –3
B 0, 0 –2, 2
A zero-sum game

Main article: Zero-sum (game theory)
Zero-sum games are a special case of constant-sum games, in which choices by players can neither increase nor decrease the available resources. In zero-sum games the total benefit to all players in the game, for every combination of strategies, always adds to zero (more informally, a player benefits only at the equal expense of others). Poker exemplifies a zero-sum game (ignoring the possibility of the house's cut), because one wins exactly the amount one's opponents lose. Other zero-sum games include matching pennies and most classical board games including Go and chess.

Many games studied by game theorists (including the famous prisoner's dilemma) are non-zero-sum games, because some outcomes have net results greater or less than zero. Informally, in non-zero-sum games, a gain by one player does not necessarily correspond with a loss by another.

Constant-sum games correspond to activities like theft and gambling, but not to the fundamental economic situation in which there are potential gains from trade. It is possible to transform any game into a (possibly asymmetric) zero-sum game by adding an additional dummy player (often called "the board"), whose losses compensate the players' net winnings.


[edit] Simultaneous and sequential
Main article: Sequential game
Simultaneous games are games where both players move simultaneously, or if they do not move simultaneously, the later players are unaware of the earlier players' actions (making them effectively simultaneous). Sequential games (or dynamic games) are games where later players have some knowledge about earlier actions. This need not be perfect information about every action of earlier players; it might be very little knowledge. For instance, a player may know that an earlier player did not perform one particular action, while he does not know which of the other available actions the first player actually performed.

The difference between simultaneous and sequential games is captured in the different representations discussed above. Often, normal form is used to represent simultaneous games, and extensive form is used to represent sequential ones; although this isn't a strict rule in a technical sense.


[edit] Perfect information and imperfect information

A game of imperfect information (the dotted line represents ignorance on the part of player 2)Main article: Perfect information
An important subset of sequential games consists of games of perfect information. A game is one of perfect information if all players know the moves previously made by all other players. Thus, only sequential games can be games of perfect information, since in simultaneous games not every player knows the actions of the others. Most games studied in game theory are imperfect-information games, although there are some interesting examples of perfect-information games, including the ultimatum game and centipede game. Perfect-information games include also chess, go, mancala, and arimaa.

Perfect information is often confused with complete information, which is a similar concept. Complete information requires that every player know the strategies and payoffs of the other players but not necessarily the actions.


[edit] Infinitely long games
Main article: Determinacy
Games, as studied by economists and real-world game players, are generally finished in a finite number of moves. Pure mathematicians are not so constrained, and set theorists in particular study games that last for an infinite number of moves, with the winner (or other payoff) not known until after all those moves are completed.

The focus of attention is usually not so much on what is the best way to play such a game, but simply on whether one or the other player has a winning strategy. (It can be proven, using the axiom of choice, that there are games—even with perfect information, and where the only outcomes are "win" or "lose"—for which neither player has a winning strategy.) The existence of such strategies, for cleverly designed games, has important consequences in descriptive set theory.


\ Discrete and continuous games
Much of game theory is concerned with finite, discrete games, that have a finite number of players, moves, events, outcomes, etc. Many concepts can be extended, however. Continuous games allow players to choose a strategy from a continuous strategy set. For instance, Cournot competition is typically modeled with players' strategies being any non-negative quantities, including fractional quantities.

Differential games such as the continuous pursuit and evasion game are continuous games.


\ One-player and many-player games
Individual decision problems are sometimes considered "one-player games". While these situations are not game theoretical, they are modeled using many of the same tools within the discipline of decision theory. It is only with two or more players that a problem becomes game theoretical. A randomly acting player who makes "chance moves", also known as "moves by nature", is often added (Osborne & Rubinstein 1994). This player is not typically considered a third player in what is otherwise a two player game, but merely serves to provide a roll of the dice where required by the game. Games with an infinite number of players are often called n-person games (Luce & Raiffa 1957).
\ Metagames
These are games the play of which is the development of the rules for another game, the target or subject game. Metagames seek to maximize the utility value of the rule set developed. The theory of metagames is related to mechanism design theory.


\ History
The first known discussion of game theory occurred in a letter written by James Waldegrave in 1713. In this letter, Waldegrave provides a minimax mixed strategy solution to a two-person version of the card game le Her.

James Madison made what we now recognize as a game-theoretic analysis of the ways states can be expected to behave under different systems of taxation.[11][12]

It was not until the publication of Antoine Augustin Cournot's Recherches sur les principes mathématiques de la théorie des richesses (Researches into the Mathematical Principles of the Theory of Wealth) in 1838 that a general game theoretic analysis was pursued. In this work Cournot considers a duopoly and presents a solution that is a restricted version of the Nash equilibrium.

Although Cournot's analysis is more general than Waldegrave's, game theory did not really exist as a unique field until John von Neumann published a series of papers in 1928. While the French mathematician Émile Borel did some earlier work on games, Von Neumann can rightfully be credited as the inventor of game theory. Von Neumann was a brilliant mathematician whose work was far-reaching from set theory to his calculations that were key to development of both the Atom and Hydrogen bombs and finally to his work developing computers. Von Neumann's work in game theory culminated in the 1944 book Theory of Games and Economic Behavior by von Neumann and Oskar Morgenstern. This profound work contains the method for finding mutually consistent solutions for two-person zero-sum games. During this time period, work on game theory was primarily focused on cooperative game theory, which analyzes optimal strategies for groups of individuals, presuming that they can enforce agreements between them about proper strategies.

In 1950, the first discussion of the prisoner's dilemma appeared, and an experiment was undertaken on this game at the RAND corporation. Around this same time, John Nash developed a criterion for mutual consistency of players' strategies, known as Nash equilibrium, applicable to a wider variety of games than the criterion proposed by von Neumann and Morgenstern. This equilibrium is sufficiently general to allow for the analysis of non-cooperative games in addition to cooperative ones.

Game theory experienced a flurry of activity in the 1950s, during which time the concepts of the core, the extensive form game, fictitious play, repeated games, and the Shapley value were developed. In addition, the first applications of Game theory to philosophy and political science occurred during this time.

In 1965, Reinhard Selten introduced his solution concept of subgame perfect equilibria, which further refined the Nash equilibrium (later he would introduce trembling hand perfection as well). In 1967, John Harsanyi developed the concepts of complete information and Bayesian games. Nash, Selten and Harsanyi became Economics Nobel Laureates in 1994 for their contributions to economic game theory.

In the 1970s, game theory was extensively applied in biology, largely as a result of the work of John Maynard Smith and his evolutionarily stable strategy. In addition, the concepts of correlated equilibrium, trembling hand perfection, and common knowledge[13] were introduced and analysed.

In 2005, game theorists Thomas Schelling and Robert Aumann followed Nash, Selten and Harsanyi as Nobel Laureates. Schelling worked on dynamic models, early examples of evolutionary game theory. Aumann contributed more to the equilibrium school, introducing an equilibrium coarsening, correlated equilibrium, and developing an extensive formal analysis of the assumption of common knowledge and of its consequences.

In 2007, Roger Myerson, together with Leonid Hurwicz and Eric Maskin, was awarded of the Nobel Prize in Economics "for having laid the foundations of mechanism design theory." Among his contributions, is also the notion of proper equilibrium, and an important graduate text: Game Theory, Analysis of Conflict (Myerson 1997).


[edit] See also
Combinatorial game theory
Glossary of game theory
List of games in game theory
Quantum game theory
Self-confirming_equilibrium

[edit] Notes
1.^ Ross, Don. "Game Theory". The Stanford Encyclopedia of Philosophy (Spring 2008 Edition). Edward N. Zalta (ed.). http://plato.stanford.edu/archives/spr2008/entries/game-theory/. Retrieved on 2008-08-21.
2.^ Experimental work in game theory goes by many names, experimental economics, behavioral economics, and behavioural game theory are several. For a recent discussion on this field see Camerer (2003).
3.^ Evolutionary Game Theory (Stanford Encyclopedia of Philosophy)
4.^ a b Biological Altruism (Stanford Encyclopedia of Philosophy)
5.^ Algorithmic Game Theory. http://www.cambridge.org/journals/nisan/downloads/Nisan_Non-printable.pdf.
6.^ E. Ullmann Margalit, The Emergence of Norms, Oxford University Press, 1977. C. Bicchieri, The Grammar of Society: the Nature and Dynamics of Social Norms, Cambridge University Press, 2006.
7.^ "Self-Refuting Theories of Strategic Interaction: A Paradox of Common Knowledge ", Erkenntnis 30, 1989: 69-85. See also Rationality and Coordination, Cambridge University Press, 1993.
8.^ The Dynamics of Rational Deliberation, Harvard University Press, 1990.
9.^ "Knowledge, Belief, and Counterfactual Reasoning in Games." In Cristina Bicchieri, Richard Jeffrey, and Brian Skyrms, eds., The Logic of Strategy. New York: Oxford University Press, 1999.
10.^ For a more detailed discussion of the use of Game Theory in ethics see the Stanford Encyclopedia of Philosophy's entry game theory and ethics.
11.^ James Madison, Vices of the Political System of the United States, April, 1787. Link
12.^ Jack Rakove, "James Madison and the Constitution", History Now, Issue 13 September 2007. Link
13.^ Although common knowledge was first discussed by the philosopher David Lewis in his dissertation (and later book) Convention in the late 1960s, it was not widely considered by economists until Robert Aumann's work in the 1970s.

[edit] References
Wikibooks has a book on the topic of
Introduction to Game Theory
Wikiversity has learning materials about Game Theory
Look up game theory in
Wiktionary, the free dictionary.
Wikimedia Commons has media related to: Game theory

\Textbooks and general references
Aumann, Robert J. (1987), "game theory,", The New Palgrave: A Dictionary of Economics, 2, pp. 460–82 .
_____ (2008). "game theory," The New Palgrave Dictionary of Economics. 2nd Edition. Abstract.
Dutta, Prajit K. (1999), Strategies and games: theory and practice, MIT Press, ISBN 978-0-262-04169-0 . Suitable for undergraduate and business students.
Fernandez, L F.; Bierman, H S. (1998), Game theory with economic applications, Addison-Wesley, ISBN 978-0-201-84758-1 . Suitable for upper-level undergraduates.
Fudenberg, Drew; Tirole, Jean (1991), Game theory, MIT Press, ISBN 978-0-262-06141-4 . Acclaimed reference text, public description.
Gibbons, Robert D. (1992), Game theory for applied economists, Princeton University Press, ISBN 978-0-691-00395-5 . Suitable for advanced undergraduates.
Published in Europe as Robert Gibbons (2001), A Primer in Game Theory, London: Harvester Wheatsheaf, ISBN 978-0-7450-1159-2 .
Gintis, Herbert (2000), Game theory evolving: a problem-centered introduction to modeling strategic behavior, Princeton University Press, ISBN 978-0-691-00943-8
Green, Jerry R.; Mas-Colell, Andreu; Whinston, Michael D. (1995), Microeconomic theory, Oxford University Press, ISBN 978-0-19-507340-9 . Presents game theory in formal way suitable for graduate level.
Gul, Faruk (2008). "behavioural economics and game theory," The New Palgrave Dictionary of Economics. 2nd Edition. Abstract.
edited by Vincent F. Hendricks, Pelle G. Hansen. (2007), Hansen, Pelle G.; Hendricks, Vincent F., eds., Game Theory: 5 Questions, New York, London: Automatic Press / VIP, ISBN 9788799101344 . Snippets from interviews.
Isaacs, Rufus (1999), Differential Games: A Mathematical Theory With Applications to Warfare and Pursuit, Control and Optimization, New York: Dover Publications, ISBN 978-0-486-40682-4
Leyton-Brown, Kevin; Shoham, Yoav (2008), Essentials of Game Theory: A Concise, Multidisciplinary Introduction, San Rafael, CA: Morgan & Claypool Publishers, ISBN 978-1-598-29593-1, http://www.gtessentials.org . An 88-page mathematical introduction; free online at many universities.
Miller, James H. (2003), Game theory at work: how to use game theory to outthink and outmaneuver your competition, New York: McGraw-Hill, ISBN 978-0-07-140020-6 . Suitable for a general audience.
Myerson, Roger B. (1997), Game theory: analysis of conflict, Harvard University Press, ISBN 978-0-674-34116-6
Osborne, Martin J. (2004), An introduction to game theory, Oxford University Press, ISBN 978-0-19-512895-6 . Undergraduate textbook.
Osborne, Martin J.; Rubinstein, Ariel (1994), A course in game theory, MIT Press, ISBN 978-0-262-65040-3 . A modern introduction at the graduate level.
Poundstone, William (1992), Prisoner's Dilemma: John von Neumann, Game Theory and the Puzzle of the Bomb, Anchor, ISBN 978-0-385-41580-4 . A general history of game theory and game theoreticians.
Rasmusen, Eric (2006), Games and Information: An Introduction to Game Theory (4th ed.), Wiley-Blackwell, ISBN 978-1-4051-3666-2, http://www.rasmusen.org/GI/index.html
Shoham, Yoav; Leyton-Brown, Kevin (2009), Multiagent Systems: Algorithmic, Game-Theoretic, and Logical Foundations, New York: Cambridge University Press, ISBN 978-0-521-89943-7, http://www.masfoundations.org . A comprehensive reference from a computational perspective; downloadable free online.
Williams, John Davis (1954) (PDF), The Compleat Strategyst: Being a Primer on the Theory of Games of Strategy, Santa Monica: RAND Corp., ISBN 9780833042224, http://www.rand.org/pubs/commercial_books/2007/RAND_CB113-1.pdf Praised primer and popular introduction for everybody, never out of print.

[edit] Historically important texts
Aumann, R.J. and Shapley, L.S. (1974), Values of Non-Atomic Games, Princeton University Press
Cournot, A. Augustin (1838), "Recherches sur les principles mathematiques de la théorie des richesses", Libraire des sciences politiques et sociales (Paris: M. Rivière & C.ie)
Edgeworth, Francis Y. (1881), Mathematical Psychics, London: Kegan Paul
Fisher, Ronald (1930), The Genetical Theory of Natural Selection, Oxford: Clarendon Press
reprinted edition: R.A. Fisher ; edited with a foreword and notes by J.H. Bennett. (1999), The Genetical Theory of Natural Selection: A Complete Variorum Edition, Oxford University Press, ISBN 978-0-19-850440-5
Luce, R. Duncan; Raiffa, Howard (1957), Games and decisions: introduction and critical survey, New York: Wiley
reprinted edition: R. Duncan Luce ; Howard Raiffa (1989), Games and decisions: introduction and critical survey, New York: Dover Publications, ISBN 978-0-486-65943-5
Maynard Smith, John (1982), Evolution and the theory of games, Cambridge University Press, ISBN 978-0-521-28884-2
Smith, John Maynard; Price, George R. (1973), "The logic of animal conflict", Nature 246: 15–18, doi:10.1038/246015a0
Nash, John (1950), "Equilibrium points in n-person games", Proceedings of the National Academy of Sciences of the United States of America 36 (1): 48–49, doi:10.1073/pnas.36.1.48, http://www.pnas.org/cgi/search?sendit=Search&pubdate_year=&volume=&firstpage=&DOI=&author1=nash&author2=&title=equilibrium&andorexacttitle=and&titleabstract=&andorexacttitleabs=and&fulltext=&andorexactfulltext=and&fmonth=Jan&fyear=1915&tmonth=Feb&tyear=2008&fdatedef=15+January+1915&tdatedef=6+February+2008&tocsectionid=all&RESULTFORMAT=1&hits=10&hitsbrief=25&sortspec=relevance&sortspecbrief=relevance
Shapley, L.S. (1953), A Value for n-person Games, In: Contributions to the Theory of Games volume II, H.W. Kuhn and A.W. Tucker (eds.)
Shapley, L.S. (1953), Stochastic Games, Proceedings of National Academy of Science Vol. 39, pp. 1095–1100.
von Neumann, John (1928), "Zur Theorie der Gesellschaftspiele" ([dead link] – Scholar search), Mathematische Annalen 100 (1): 295–320, doi:10.1007/BF01448847, http://www.digizeitschriften.de/home/services/pdfterms/?ID=363311
von Neumann, John; Morgenstern, Oskar (1944), Theory of games and economic behavior, Princeton University Press
Zermelo, Ernst (1913), "Über eine Anwendung der Mengenlehre auf die Theorie des Schachspiels", Proceedings of the Fifth International Congress of Mathematicians 2: 501–4

[edit] Other print references
Ben David, S.; Borodin, Allan; Karp, Richard; Tardos, G.; Wigderson, A. (1994), "On the Power of Randomization in On-line Algorithms" (PDF), Algorithmica 11 (1): 2–14, doi:10.1007/BF01294260, http://www.math.ias.edu/~avi/PUBLICATIONS/MYPAPERS/BORODIN/paper.pdf
Bicchieri, Cristina (1993, 2nd. edition, 1997), Rationality and Coordination, Cambridge University Press, ISBN 0-521-57444-7
Camerer, Colin (2003), Behavioral game theory: experiments in strategic interaction, Russesll Sage Foundation, ISBN 978-0-691-09039-9
Downs, Anthony (1957), An Economic theory of Democracy, New York: Harper
Gauthier, David (1986), Morals by agreement, Oxford University Press, ISBN 978-0-19-824992-4
Grim, Patrick; Kokalis, Trina; Alai-Tafti, Ali; Kilb, Nicholas; St Denis, Paul (2004), "Making meaning happen", Journal of Experimental & Theoretical Artificial Intelligence 16 (4): 209–243, doi:10.1080/09528130412331294715
Harper, David; Maynard Smith, John (2003), Animal signals, Oxford University Press, ISBN 978-0-19-852685-8
Harsanyi, John C. (1974), "An equilibrium point interpretation of stable sets", Management Science 20: 1472–1495, doi:10.1287/mnsc.20.11.1472
Kavka, Gregory S. (1986), Hobbesian moral and political theory, Princeton University Press, ISBN 978-0-691-02765-4
Levy, Gilat; Razin, Ronny (2003), "It Takes Two: An Explanation of the Democratic Peace", Working Paper, http://papers.ssrn.com/sol3/papers.cfm?abstract_id=433844
Lewis, David (1969), Convention: A Philosophical Study , ISBN 978-0-631-23257-5 (2002 edition)
McDonald, John (1950 - 1996), Strategy in Poker, Business & War, W. W. Norton, ISBN 0-393-31457-X . A layman's introduction.
Quine, W.v.O (1967), "Truth by Convention", Philosophica Essays for A.N. Whitehead, Russel and Russel Publishers, ISBN 978-0-8462-0970-6
Quine, W.v.O (1960), "Carnap and Logical Truth", Synthese 12 (4): 350–374, doi:10.1007/BF00485423
Siegfried, Tom (2006), A Beautiful Math, Joseph Henry Press, ISBN 0-309-10192-1
Skyrms, Brian (1990), The Dynamics of Rational Deliberation, Harvard University Press, ISBN 0-674-21885-X
Skyrms, Brian (1996), Evolution of the social contract, Cambridge University Press, ISBN 978-0-521-55583-8
Skyrms, Brian (2004), The stag hunt and the evolution of social structure, Cambridge University Press, ISBN 978-0-521-53392-8
Sober, Elliott; Wilson, David Alec (1999), Unto others: the evolution and psychology of unselfish behavior, Harvard University Press, ISBN 978-0-674-93047-6
Thrall, Robert M.; Lucas, William F. (1963), "n-person games in partition function form", Naval Research Logistics Quarterly 10 (4): 281–298, doi:10.1002/nav.3800100126

[edit] Websites
Paul Walker: History of Game Theory Page.
David Levine: Game Theory. Papers, Lecture Notes and much more stuff.
Alvin Roth: Game Theory and Experimental Economics page - Comprehensive list of links to game theory information on the Web
Adam Kalai: Game Theory and Computer Science - Lecture notes on Game Theory and Computer Science
Mike Shor: Game Theory .net - Lecture notes, interactive illustrations and other information.
Jim Ratliff's Graduate Course in Game Theory (lecture notes).
Valentin Robu's software tool for simulation of bilateral negotiation (bargaining)
Don Ross: Review Of Game Theory in the Stanford Encyclopedia of Philosophy.
Bruno Verbeek and Christopher Morris: Game Theory and Ethics
Chris Yiu's Game Theory Lounge
Elmer G. Wiens: Game Theory - Introduction, worked examples, play online two-person zero-sum games.
Marek M. Kaminski: Game Theory and Politics - syllabuses and lecture notes for game theory and political science.
Web sites on game theory and social interactions
Kesten Green's Conflict Forecasting - See Papers for evidence on the accuracy of forecasts from game theory and other methods.
McKelvey, Richard D., McLennan, Andrew M., and Turocy, Theodore L. (2007) Gambit: Software Tools for Game Theory.
Ben Polak: Open Course on Game Theory at Yale videos of the course
[hide]v • d • eTopics in game theory

Definitions Normal-form game · Extensive-form game · Cooperative game · Information set · Preference

Equilibrium concepts Nash equilibrium · Subgame perfection · Bayesian-Nash · Perfect Bayesian · Trembling hand · Proper equilibrium · Epsilon-equilibrium · Correlated equilibrium · Sequential equilibrium · Quasi-perfect equilibrium · Evolutionarily stable strategy · Risk dominance · Pareto efficiency · Quantal response equilibrium · Self-confirming equilibrium

Strategies Dominant strategies · Pure strategy · Mixed strategy · Tit for tat · Grim trigger · Collusion · Backward induction

Classes of games Symmetric game · Perfect information · Dynamic game · Sequential game · Repeated game · Signaling game · Cheap talk · Zero-sum game · Mechanism design · Bargaining problem · Stochastic game · Large poisson game · Nontransitive game · Global games

Games Prisoner's dilemma · Traveler's dilemma · Coordination game · Chicken · Centipede game · Volunteer's dilemma · Dollar auction · Battle of the sexes · Stag hunt · Matching pennies · Ultimatum game · Minority game · Rock-paper-scissors · Pirate game · Dictator game · Public goods game · Blotto games · War of attrition · El Farol Bar problem · Cake cutting · Cournot game · Deadlock · Diner's dilemma · Guess 2/3 of the average · Kuhn poker · Nash bargaining game · Screening game · Trust game · Princess and monster game

Theorems Minimax theorem · Purification theorem · Folk theorem · Revelation principle · Arrow's impossibility theorem

See also Tragedy of the commons · All-pay auction · List of games in game theory




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Money

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Money is anything that is generally accepted as payment for goods and services and repayment of debts.[1] The main uses of money are as a medium of exchange, a unit of account, and a store of value.[2] Some authors explicitly require money to be a standard of deferred payment.[3] The dominant form of money is currency[counterfactual].[4][5]

The term "price system" is sometimes used to refer to methods using commodity valuation or money accounting systems.

The word "money" is believed to originate from a temple of Hera, located on Capitoline, one of Rome's seven hills. In the ancient world Hera was often associated with money. The temple of Juno Moneta at Rome was the place where the mint of Ancient Rome was located.[6] The name "Juno" may derive from the Etruscan goddess Uni (which means "the one", "unique", "unit", "union", "united") and "Moneta" either from the Latin word "monere" (remind, warn, or instruct) or the Greek word "moneres" (alone, unique).

Contents [hide]
1 Economic characteristics
1.1 Medium of exchange
1.2 Unit of account
1.3 Store of value
2 Market liquidity
3 Types of money
3.1 Commodity money
3.2 Representative money
3.3 Credit money
3.4 Fiat money
3.5 Money supply
3.6 Monetary policy
4 History of money
5 See also
6 References



Economic characteristics
Money is generally considered to have the following characteristics, which are summed up in a rhyme found in older economics textbooks: "Money is a matter of functions four, a medium, a measure, a standard, a store." That is, money functions as a medium of exchange, a unit of account, a standard of deferred payment, and a store of value.[2][7][8]

There have been many historical arguments regarding the combination of money's functions, some arguing that they need more separation and that a single unit is insufficient to deal with them all. One of these arguments is that the role of money as a medium of exchange is in conflict with its role as a store of value: its role as a store of value requires holding it without spending, whereas its role as a medium of exchange requires it to circulate.[8] Others argue that storing of value is just deferral of the exchange, but does not diminish the fact that money is a medium of exchange that can be transported both across space and time.[9] 'Financial capital' is a more general and inclusive term for all liquid instruments, whether or not they are a uniformly recognized tender.


Medium of exchange
Main article: Medium of exchange
Money is used as an intermediary for trade, in order to avoid the inefficiencies of a barter system, which are sometimes referred to as the 'double coincidence of wants problem'. Such usage is termed a medium of exchange.


Unit of account
Main article: Unit of account
A unit of account is a standard numerical unit of measurement of the market value of goods, services, and other transactions. Also known as a "measure" or "standard" of relative worth and deferred payment, a unit of account is a necessary prerequisite for the formulation of commercial agreements that involve debt.

Divisible into small units without destroying their value; precious metals can be coined from bars, or melted down into bars again.
Fungible: that is, one unit or piece must be perceived as equivalent to any other, which is why diamonds, works of art or real estate are not suitable as money.
A specific weight, or measure, or size to be verifiably countable. For instance, coins are often made with ridges around the edges, so that any removal of material from the coin (lowering its commodity value) will be easy to detect.

Store of value
Main article: Store of value
To act as a store of value, a commodity, a form of money, or financial capital must be able to be reliably saved, stored, and retrieved — and be predictably useful when it is so retrieved. Fiat currency like paper or electronic money no longer backed by gold in most countries is not considered by some economists to be a store of value.


Market liquidity
Main article: Market liquidity
Liquidity describes how easily an item can be traded for another item, or into the common currency within an economy. Money is the most liquid asset because it is universally recognised and accepted as the common currency. In this way, money gives consumers the freedom to trade goods and services easily without having to barter.

Liquid financial instruments are easily tradable and have low transaction costs. There should be no — or minimal — spread between the prices to buy and sell the instrument being used as money.


Types of money
In economics, money is a broad term that refers to any financial instrument that can fulfill the functions of money (detailed above). Modern monetary theory distinguishes among different types of monetary aggregates, using a categorization system that focuses on the liquidity of the financial instrument used as money.


Commodity money
Main article: Commodity money
Commodity money value comes from the commodity out of which it is made. The commodity itself constitutes the money, and the money is the commodity.[10] Examples of commodities that have been used as mediums of exchange include gold, silver, copper, rice, salt, peppercorns, large stones, decorated belts, shells, alcohol, cigarettes, cannabis, candy, barley, etc. These items were sometimes used in a metric of perceived value in conjunction to one another, in various commodity valuation or Price System economies. Use of commodity money is similar to barter, but a commodity money provides a simple and automatic unit of account for the commodity which is being used as money.


Representative money
Main article: Representative money
Representative money is money that consists of token coins, other physical tokens such as certificates, and even non-physical "digital certificates" (authenticated digital transactions) that can be reliably exchanged for a fixed quantity of a commodity such as gold, silver or potentially water, oil or food. Representative money thus stands in direct and fixed relation to the commodity which backs it, while not itself being composed of that commodity.



Banknotes from all around the world donated by visitors to the British Museum, London.
Credit money
Main article: Credit money
Credit money is any claim against a physical or legal person that can be used for the purchase of goods and services.[10] Credit money differs from commodity and fiat money in two ways: It is not payable on demand (although in the case of fiat money, "demand payment" is a purely symbolic act since all that can be demanded is other types of fiat currency) and there is some element of risk that the real value upon fulfillment of the claim will not be equal to real value expected at the time of purchase.[10]

This risk comes about in two ways and affects both buyer and seller.

First it is a claim and the claimant may default (not pay). High levels of default have destructive supply side effects. If manufacturers and service providers do not receive payment for the goods they produce, they will not have the resources to buy the labor and materials needed to produce new goods and services. This reduces supply, increases prices and raises unemployment, possibly triggering a period of stagflation. In extreme cases, widespread defaults can cause a lack of confidence in lending institutions and lead to economic depression. For example, abuse of credit arrangements is considered one of the significant causes of the Great Depression of the 1930s.[11]

The second source of risk is time. Credit money is a promise of future payment. If the interest rate on the claim fails to compensate for the combined impact of the inflation (or deflation) rate and the time value of money, the seller will receive less real value than anticipated. If the interest rate on the claim overcompensates, the buyer will pay more than expected.

The process of fractional-reserve banking has a cumulative effect of money creation by banks.


Fiat money
Main article: Fiat money
Fiat money is any money whose value is determined by legal means. The terms fiat currency and fiat money relate to types of currency or money whose usefulness results not from any intrinsic value or guarantee that it can be converted into gold or another currency, but instead from a government's order (fiat) that it must be accepted as a means of payment.[12][13]

Fiat money is created when a type of credit money (typically notes from a central bank, such as the Federal Reserve System in the U.S.) is declared by a government act (fiat) to be acceptable and officially-recognized payment for all debts, both public and private. Fiat money may thus be symbolic of a commodity or a government promise, though not a completely specified amount of either of these. Fiat money is thus not technically fungible or tradable directly for fixed quantities of anything, except more of the same government's fiat money. Fiat moneys usually trade against each other in value in an international market, as with other goods. An exception to this is when currencies are locked to each other, as explained below. Many but not all fiat moneys are accepted on the international market as having value. Those that are trade indirectly against any internationally available goods and services.[10] Thus the number of U.S. dollars or Japanese yen which are equivalent to each other, or to a gram of gold metal, are all market decisions which change from moment to moment on a daily basis. Occasionally, a country will peg the value of its fiat money to that of the fiat money of a larger economy: for example the Belize dollar trades in fixed proportion (at 2:1) to the U.S. dollar, so there is no floating value ratio of the two currencies.

Fiat money, if physically represented in the form of currency (paper or coins) can be easily damaged or destroyed. However, here fiat money has an advantage over representative or commodity money, in that the same laws that created the money can also define rules for its replacement in case of damage or destruction. For example, the U.S. government will replace mutilated federal reserve notes (U.S. fiat money) if at least half of the physical note can be reconstructed, or if it can be otherwise proven to have been destroyed.[14] By contrast, commodity money which has been destroyed or lost is gone.


Money supply
Main article: Money supply
The money supply is the amount of money within a specific economy available for purchasing goods or services. The supply in the US is usually considered as four escalating categories M0, M1, M2 and M3. The categories grow in size with M3 representing all forms of money (including credit) and M0 being just base money (coins, bills, and central bank deposits). M0 is also money that can satisfy private banks' reserve requirements. In the US, the Federal Reserve is responsible for controlling the money supply, while in the Euro area the respective institution is the European Central Bank. Other central banks with significant impact on global finances are the Bank of Japan, People's Bank of China and the Bank of England.

When gold is used as money, the money supply can grow in either of two ways. First, the money supply can increase as the amount of gold increases by new gold mining at about 2% per year, but it can also increase more during periods of gold rushes and discoveries, such as when Columbus discovered the new world and brought gold back to Spain, or when gold was discovered in California in 1848. This kind of increase helps debtors, and causes inflation, as the value of gold goes down. Second, the money supply can increase when the value of gold goes up. This kind of increase in the value of gold helps savers and creditors and is called deflation, where items for sale are less expensive in terms of gold. Deflation was the more typical situation for over a century when gold and credit money backed by gold were used as money in the US from 1792 to 1913.


Monetary policy
Main article: Monetary policy
Monetary policy is the process by which a government, central bank, or monetary authority manages the money supply to achieve specific goals. Usually the goal of monetary policy is to accommodate economic growth in an environment of stable prices. For example, it is clearly stated in the Federal Reserve Act that the Board of Governors and the Federal Open Market Committee should seek “to promote effectively the goals of maximum employment, stable prices, and moderate long-term interest rates.”[15]

A failed monetary policy can have significant detrimental effects on an economy and the society that depends on it. These include hyperinflation, stagflation, recession, high unemployment, shortages of imported goods, inability to export goods, and even total monetary collapse and the adoption of a much less efficient barter economy. This happened in Russia, for instance, after the fall of the Soviet Union.

Governments and central banks have taken both regulatory and free market approaches to monetary policy. Some of the tools used to control the money supply include:

changing the interest rate at which the government loans or borrows money
currency purchases or sales
increasing or lowering government borrowing
increasing or lowering government spending
manipulation of exchange rates
raising or lowering bank reserve requirements
regulation or prohibition of private currencies
taxation or tax breaks on imports or exports of capital into a country
For many years much of monetary policy was influenced by an economic theory known as monetarism. Monetarism is an economic theory which argues that management of the money supply should be the primary means of regulating economic activity. The stability of the demand for money prior to the 1980s was a key finding of Milton Friedman and Anna Schwartz[16] supported by the work of David Laidler,[17] and many others.

The nature of the demand for money changed during the 1980s owing to technical, institutional, and legal factors and the influence of monetarism has since decreased.


History of money

Himba woman covered with a traditional ochre pigment.Main article: History of money
The use of barter-like methods may date back to at least 100,000 years ago, though contrary to popular conception, there is no evidence of a society or economy that relied primarily on barter.[18] Instead, non-monetary societies operated largely along the principles of gift economics. When barter did in fact occur, it was usually between either complete strangers or would-be enemies.[19] Trading in red ochre is attested in Swaziland, shell jewellery in the form of strung beads also dates back to this period, and had the basic attributes needed of commodity money. To organize production and to distribute goods and services among their populations, before market economies existed, people relied on tradition, top-down command, or community cooperation.

The Shekel referred to an ancient unit of weight and currency. The first usage of the term came from Mesopotamia circa 3000 BC. and referred to a specific mass of barley which related other values in a metric such as silver, bronze, copper etc. A barley/shekel was originally both a unit of currency and a unit of weight.[20]


A 640 BCE one-third stater electrum coin from Lydia, shown larger.According to Herodotus, and most modern scholars, the Lydians were the first people to introduce the use of gold and silver coin.[21] It is thought that these first stamped coins were minted around 650-600 BC.[22] A stater coin was made in the stater (trite) denomination. To complement the stater, fractions were made: the trite (third), the hekte (sixth), and so forth in lower denominations.

The name of Croesus of Lydia became synonymous with wealth in antiquity. Sardis was renowned as a beautiful city. Around 550 BC, Croesus contributed money for the construction of the temple of Artemis at Ephesus, one of the Seven Wonders of the ancient world.

The first banknotes were used in China in the 7th century, and the first in Europe issued by Stockholms Banco in 1661.

In the Western world, a prevalent term for coin-money has been specie, stemming from Latin in specie "in kind".[23]


See also
Numismatics portal
Wikiquote has a collection of quotations related to: Money
Look up money in
Wiktionary, the free dictionary.
Wikimedia Commons has media related to: Money

Coin of account
Counterfeit#Counterfeiting of Money
Currency market
Electronic money
Fractional reserve banking
Full reserve banking
Labor-time voucher
Local Exchange Trading Systems
Monetary economics
Non-market economics
Numismatics — Collection and study of money
Seignorage
World currency

References
1.^ Mishkin, Frederic S. (2007). The Economics of Money, Banking, and Financial Markets (Alternate Edition). Boston: Addison Wesley. p. 8. ISBN 0-321-42177-9.
2.^ a b Mankiw, N. Gregory (2007). Macroeconomics (6th ed.). New York: Worth Publishers. ISBN 0-7167-6213-7.
3.^ "amosweb.com". amosweb.com. http://www.amosweb.com/cgi-bin/awb_nav.pl?s=wpd&c=dsp&k=standard%20of%20deferred%20payment. Retrieved on 2009-04-20.
4.^ "Learn More About Coins and Money — Treasure Trove - Philadelphia Fed". Philadelphia Fed.. http://www.philadelphiafed.org/education/money-in-motion/treasure-trove/. Retrieved on 2009-04-20.
5.^ "On2 Money / A History of Money". Pbs.org. http://www.pbs.org/newshour/on2/money/history.html. Retrieved on 2009-04-20.
6.^ D'Eprio, Peter & Pinkowish, Mary Desmond (1998). What Are The Seven Wonders Of The World? First Anchor Books, p.192. ISBN 0-385-49062-3
7.^ Krugman, Paul & Wells, Robin, Economics, Worth Publishers, New York (2006)
8.^ a b T.H. Greco. Money: Understanding and Creating Alternatives to Legal Tender, White River Junction, Vt: Chelsea Green Publishing (2001). ISBN 1-890132-37-3
9.^ Theory of Money and Credit – Library of Economics and Liberty
10.^ a b c d Mises, Ludwig von. The Theory of Money and Credit, (Indianapolis, IN: Liberty Fund, Inc., 1981), trans. H. E. Batson. Available online here [1]; accessed 9 May 2007; Part One: The Nature of Money, Chapter 3: The Various Kinds of Money, Section 3: Commodity Money, Credit Money, and Fiat Money, Paragraph 25.
11.^ Barry Eichengreen and Kris Mitchener, "The Great Depression as a credit boom gone wrong", Bank For International Settlements, Working Papers No. 137 (September 2003). Retrieved 2007-05-08.
12.^ Deardorff, Prof. Alan V. (2008). "Deardorff's Glossary of International Economics". Department of Economics, University of Michigan. http://www-personal.umich.edu/~alandear/glossary/f.html.
13.^ Black, Henry Campbell (1910). "A Law Dictionary Containing Definitions Of The Terms And Phrases Of American And English Jurisprudence, Ancient And Modern", page 494. West Publishing Co. Black’s Law Dictionary defines the word "fiat" to mean "a short order or warrant of a Judge or magistrate directing some act to be done; an authority issuing from some competent source for the doing of some legal act"
14.^ Shredded & mutilated: Mutilated Currency, Bureau of Engraving and Printing. Retrieved 2007-05-09.
15.^ The Federal Reserve. 'Monetary Policy and the Economy". Board of Governors of the Federal Reserve System, (2005-07-05). Retrieved 2007-05-15.
16.^ Milton Friedman, Anna Jacobson Schwartz, (1971). Monetary History of the United States, 1867–1960. Princeton, N.J: Princeton University Press. ISBN 0-691-00354-8.
17.^ David Laidler, (1997). Money and Macroeconomics: The Selected Essays of David Laidler (Economists of the Twentieth Century). Edward Elgar Publishing. ISBN 1-85898-596-X.
18.^ Mauss, Marcel. 'The Gift: The Form and Reason for Exchange in Archaic Societies.' pp. 36-37.
19.^ Graeber, David. 'Toward an Anthropological Theory of Value'. pp. 153-154.
20.^ Kramer, History Begins at Sumer, pp. 52–55.
21.^ Herodotus. Histories, I, 94
22.^ "Goldsborough, Reid. "World's First Coin"". Rg.ancients.info. 2003-10-02. http://rg.ancients.info/lion/article.html. Retrieved on 2009-04-20.
23.^ "Online Etymology Dictionary". Etymonline.com. http://www.etymonline.com/index.php?search=specie&searchmode=phrase. Retrieved on 2009-04-20.
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