Evaluating The Validity Of The PPP Hypothesis A Time Series Analysis Dissertation

Evaluating The Validity Of The PPP Hypothesis A Time Series Analysis Of The US-UK Exchange Rate - Dissertation Example Although significant coefficients in this regression seems to indicate that variations in the price level differential lead to changes in the exchange rate, deeper inspection of the stationarity properties of the relevant series establishes that we actually fail to find any evidence to support that PPP holds for the two countries under question. However since the time period covered is only of a short duration of 37 years, we conclude that this evidence should not be taken to be conclusive. It could still be the case that PPP holds in the long run but what has been examined in this paper covers only the short run and during this period the exchange rate is at a perturbed state. Introduction The exchange rate is one of the most important macro variables that have significant implications for policy of any open economy. It is therefore of primary importance to identify what determines the long run real exchange rate between two currencies for either of the countries involved. Additiona lly, given the state of other macro variables what should be expected of the medium and long term dynamics of the exchange rate for any given economy? That is, should it be expected to appreciate or depreciate over time? How does the nominal exchange rate affect inflation? These are all critical questions can be answered using the Purchasing Power Parity (PPP) theory. It is therefore critical to evaluate its empirical validity. The vital notion of the PPP hypothesis is that the real rate of exchange between the currencies of any two countries is determined essentially by the ratio of the price levels of the countries in question. ... This is essentially the implication of the law of one price which postulates that the same good should sell at the same price in all markets because if different prices are charged then arbitrage will arise until the prices are equalized. Alternatively, the theory suggests that changes in real exchange rates are essentially driven by relative price level changes (Froot and Rogoff, 1995). Now, there are absolute, relative and weak versions of the hypothesis and these are distinguished as follows. When the exchange rate is simply equal to the relative price level ratio absolute or strong PPP is said to prevail. If the variability of the exchange rate is caused by variations in the relative price levels, then we say that relative PPP holds. And finally, weak PPP is known to hold whenever changes in the relative price levels significantly affect the exchange rate. The reason that this theory has motivated a large number of studies and keeps on motivating new pursuits of empirically evalu ating the PPP theory lies in the strong potential of the theory to have strong bearing on various policy aspects. For instance, an economy which has newly become independent can utilize this theory to ascertain its exchange rate. Forecasting macro-dynamics is critical for effective policy and this theory can be utilized to forecast the medium and long term exchange rates if it is found to be a valid determinant of the exchange rate. With this as the basic premise, in the present paper, we shall evaluate the validity of the PPP hypothesis as in its capacity of predicting real exchange rates. In particular, we want to evaluate whether the PPP hypothesis