From base price levels of 100 in 1987, West German and U.S. price levels in 1988 stood at 102 and 106, respectively. If the 1987 $/DM exchange rate was $0.54, what should the exchange rate be in 1988? In fact, the exchange rate in 1988 was DM 1 = $0.56. What might account for the discrepancy? (Price levels were measured using the consumer price index.)
Answer. If e1981 is the dollar value of the German mark in 1988, then according to purchasing power parity e1988/.54 = 106/102 or e1988 = $.5612. The discrepancy between the predicted rate of $.5612 and the actual rate of $.56 is insignificant and hence needs no explaining. Historically, however, discrepancies betweenthe PPP rate and the actual rate have frequently occurred. These discrepancies could be due to mismeasurement of the relevant price indices. Estimates based on narrower price indices reflecting only traded goods prices would probably be closer to the mark, so to speak. Alternatively, it could be due to a switch in investors’ preferences from dollar to non‑dollar assets
