Purchasing power parity

Purchasing Power Parity (PPP) is a way of measuring economic variables in different countries so that irrelevant exchange rate variations do not distort comparisons. Purchasing power exchange rates are such that it would cost exactly the same number of, for example, US dollars to buy Euros and then buy a basket of goods in the market as it would cost to purchase the same goods directly with dollars. The purchasing power exchange rate used in this conversion equals the ratio of the currencies' respective purchasing powers (reciprocals of their price levels). Purchasing Power Parity (PPP) is a way of measuring economic variables in different countries so that irrelevant exchange rate variations do not distort comparisons. Purchasing power exchange rates are such that it would cost exactly the same number of, for example, US dollars to buy Euros and then buy a basket of goods in the market as it would cost to purchase the same goods directly with dollars. The purchasing power exchange rate used in this conversion equals the ratio of the currencies' respective purchasing powers (reciprocals of their price levels). In neoclassical economic theory, the purchasing power parity theory assumes that the exchange rate between two currencies actually observed in the foreign exchange market is the one that is used in the purchasing power parity comparisons, so that the same amount of goods could actually be purchased in either currency with the same beginning amount of funds. Depending on the particular theory, purchasing power parity is assumed to hold either in the long run or, more strongly, in the short run. Theories that invoke purchasing power parity assume that in some circumstances a fall in either currency's purchasing power (a rise in its price level) would lead to a proportional decrease in that currency's valuation on the foreign exchange market. The concept of purchasing power parity allows one to estimate what the exchange rate between two currencies would have to be to equate the purchasing power of the two currencies. Observed deviations of the exchange rate from purchasing power parity are measured by deviations of the real exchange rate from its PPP value. PPP exchange rates help costing but exclude profits and above all do not consider the different quality of goods among countries. The same product, for instance, can have a different level of quality and even safety in different countries, and may be subject to different taxes and transport costs. Since market exchange rates fluctuate substantially, when the GDP of one country measured in its own currency is converted to the other country's currency using market exchange rates, one country might be inferred to have higher real GDP than the other country in one year but lower in the other; both of these inferences would fail to reflect the reality of their relative levels of production. But if one country's GDP is converted into the other country's currency using PPP exchange rates instead of observed market exchange rates, the false inference will not occur. Essentially GDP measured at PPP controls for the different costs of living and price levels, usually relative to the United States dollar, enabling a more accurate estimate of a nation's level of production. The idea originated with the School of Salamanca in the 16th century, and was developed in its modern form by Gustav Cassel in 1916, in The Present Situation of the Foreign Trade.While Gustav Cassel’s use of PPP concept has been traditionally interpreted as his attempt to formulate a positive theory of exchange rate determination, the policy and theoretical context in which Cassel wrote about exchange rates suggests different interpretation. In the years immediately preceding the end of WWI and following it economists and politicians were involved in discussions on possible ways of restoring the gold standard, which would automatically restore the system of fixed exchange rates among participating nations. The stability of exchange rates was widely believed to be crucial for restoring the international trade and for its further stable and balanced growth. Nobody then was mentally prepared for the idea that flexible exchange rates determined by market forces do not necessarily cause chaos and instability in the peaceful time (and that is what the abandoning of the gold standard during the war was blamed for). Gustav Cassel was among those who supported the idea of restoring the gold standard, although with some alterations. The question, which Gustav Cassel tried to answer in his works written during that period, was not how exchange rates are determined in the free market, but rather how to determine the appropriate level at which exchange rates were to be fixed during the restoration of the system of fixed exchange rates. His recommendation was to fix exchange rates at the level corresponding to the PPP, as he believed that this would prevent trade imbalances between trading nations. Thus, PPP doctrine proposed by Cassel was not really a positive theory of exchange rate determination (as Cassel was perfectly aware of numerous factors that prevent exchange rates from stabilizing at PPP level if allowed to float), but rather a normative policy advice, formulated in the context of discussions on returning to the gold standard. The PPP concept is based on the law of one price, where in the absence of transaction costs and official trade barriers, identical goods will have the same price in different markets when the prices are expressed in the same currency.