EXTERNAL SHOCKS, PURCHASING POWER PARITY, AND THE EQUILIBRIUM REAL EXCHANGE-RATE

Two approaches are commonly used to determine the equilibrium real exc hange rate in a country after external shocks: purchasing power parity (PPP) calculations and the Salter-Swan, tradables-nontradables model. There are theoretical and empirical problems with both approaches, an d tensions between them. In this article we resolve these theoretical and empirical difficulties by presenting a model which is a generaliza tion of the Salter-Swan model and which incorporates imperfect substit utes for both imports and exports. Within the framework of this model, the definition of the real exchange rate is consistent both with that of the PPP approach and with that of the Salter-Swan model (suitably extended). Our model, however, is capable of capturing a richer set of phenomena, including terms of trade shocks and changes in foreign cap ital inflows. It also provides a practical way to estimate changes in the equilibrium real exchange rate, requiring little more information than is required to do PPP calculations. The results are consistent wi th those of multisector computable general equilibrium models, which g eneralize the trade specification of the small model.