The real exchange rate as the relative price of nontradables in terms of tradables: theoretical investigation and empirical study on French data

Large fluctuations in both nominal and real parities between G7 countries raise the issue of their determinants. This paper offers a formal description of a model of the real exchange rate, defined as the relative price of nontradables in terms of tradables, explicitly based on microeconomic optimization. Our approach relies on a version of the general equilibrium model first presented by Obsfeld-Rogoff (1996). But we enrich the model by introducing monopolistic competition in the nontradables sector. This allows for demand factors to influence the real exchange rate in the long run. Our results on French data do not corroborate the Obsfeld-Rogoff supply-side model. However, they provide some support for the extended version of the model: a cointegration relationship can be found between the real exchange rate, sectoral productivities and the « world » real interest rate, once public expenditure is also taken into account.