Effect on Exchange Rates

As we know, one of the most vital determinants of changes in relative exchange rates is the relative inflation rate. Assuming a free and open market, it is expected that an inflationary currency will depreciate against the currency having relatively stable inflation rate and the amount of depreciation will approximately equal the difference in inflation rates. The Purchasing Power Parity (PPP) theory says that spot exchange rates can shift to adjust perfectly to inflation differentials. The empirical evidence suggests that PPP gives improper reasoning for the fluctuations in the short-term exchange rate movements. In 1983, Adler and Dumas[6] discovered that concomitant inflation differentials revealed less than 5% of monthly exchange rate movements recorded in the 1970s. Although the short-term movements in exchange rates were not closely attached to the relative inflation shift, several researchers predicted that this relationship can be applicable to the longer period.

The non-existence of a strong short-term relationship can be related to the difficulty faced in calculating inflation rate and the relatively slow speed of adjustment for the change in the inflation rate observed in the goods markets. It is also possible that a foreign exchange rate, instead of adjusting exclusively on concurrent inflation rates also reflects the expected inflation rates. This suggests that current exchange rates are more affected by future expectations rather than the historical inflation rates.