Editing Exchange rate (section)

==Purchasing power of currency==
The '''real exchange rate''' ('''RER''') is the purchasing power of a currency relative to another at current exchange rates and prices. It is the ratio of the number of units of a given country's currency necessary to buy a market basket of goods in the other country, after acquiring the other country's currency in the foreign exchange market, to the number of units of the given country's currency that would be necessary to buy that market basket directly in the given country. There are various ways to measure RER.<ref name="Erlat, Guzin and Arslaner, Ferhat">{{cite journal|author1=Erlat, Guzin  |author2=Arslaner, Ferhat|title=Measuring Annual Real Exchange Rate Series for Turkey|journal=Yapi Kredi Economic Review |volume=2 |issue=8 |date=December 1997 |pages=35–61|url=https://ideas.repec.org/p/pra/mprapa/56396.html}}</ref>

Thus the real exchange rate is the exchange rate times the relative prices of a market basket of goods in the two countries. For example, the purchasing power of the [[US dollar]] relative to that of the [[euro]] is the dollar price of a euro (dollars per euro) times the euro price of one unit of the market basket (euros/goods unit) divided by the dollar price of the market basket (dollars per goods unit), and hence is dimensionless. This is the exchange rate (expressed as dollars per euro) times the relative price of the two currencies in terms of their ability to purchase units of the market basket (euros per goods unit divided by dollars per goods unit). If all goods were freely [[Tradable good|tradable]], and foreign and domestic residents purchased identical baskets of goods, [[purchasing power parity]] (PPP) would hold for the exchange rate and [[GDP deflator]]s (price levels) of the two countries, and the real exchange rate would always equal 1.

The rate of change of the real exchange rate over time for the euro versus the dollar equals the rate of appreciation of the euro (the positive or negative percentage rate of change of the dollars-per-euro exchange rate) plus the [[inflation rate]] of the euro minus the inflation rate of the dollar.