Economics 

The Big Mac index 2009 compares the price of a Big Mac sandwich across countries. The Big Mac 2009 index published by the Economist is a lighthearted guide to valuing currencies. The Big Mac index 2009 is not the best indicator of international comparison but it can provide some clues.

The Law of One Price says that identical goods should sell for the same price in two separate markets. This assumes no transportation costs and no differential taxes applied in the two markets.

In general, predatory pricing refers to anti-competitive activities taken by a company that is dominant in the market to protect its market share from new or existing competitors. Predatory pricing involves temporarily pricing a product low enough to end a competitive threat.

Price elasticity, as it relates to economics, is a measure of the responsiveness of demand or supply to a change in price. Elasticity is a measure of responsiveness.

The Consumer Price Index (CPI) is a measure that examines the weighted average of prices of a basket of consumer goods and services. It is the most commonly reported measure of the consumer price levels.

Game Theory, or Theory of Games, is a branch of mathematical and economic analysis developed to study decision making in conflict situations. Game theory analyzes strategic interactions in which the outcome of one's choices depends upon the choices of others.

Gross Domestic Product (GDP) is the broadest measure of performance of an economy. It is defined as the output of goods and services produced by labor and property located in a country.

Liquidity trap is a situation in which prevailing interest rates are low and savings rates are high. Liquidity trap makes monetary policy ineffective.

Liquidity trap also means that bank cash-holdings are rising and banks cannot find sufficient number of qualified borrowers even at extraordinary low rates of interest.

The Pigou Effect is an economics term that describes what happens in the economy, particularly with the aggregate consumption, if prices fall. It is an effect that deals with economic wealth.

The Prisoner's Dilemma is a favorite example in the game theory and social sciences that shows why co-operation is difficult to achieve even when it is mutually beneficial.

The base thesis behind the prisoner's dilemma is two prisoners having been arrested for the same offence and being held in different cells.