IVIE working papers offer in advance the results of economic research under way in order to encourage a discussion process before sending them to scientific journals for their final publication.

No abstract

Two different approaches intend to resolve the 'puzzling' slow convergence to purchasing power parity (PPP) reported in the literature [see Rogoff (1996), Journal of Economic Literature, Vol. 34.] On the one hand, there are models that consider a non-linear adjustment of real exchange rate to PPP induced by transaction costs. Such costs imply the presence of a certain transaction band where adjustment is too costly to be undertaken. On the other hand, there are models that relax the 'classical' PPP assumption of constant equilibrium real exchange rates. A prominent theory put together by BS effect, suggests that a non-constant real exchange rate equilibrium is induced by different productivity growth rates between countries. This paper reconciles those two approaches by considering an exponential smooth transition-in-deviation non-linear adjustment mechanism towards non-constant equilibrium real exchange rates within the EMS (European Monetary System) and effective rates. The equilibrium is proxied, in a theoretically appealing manner, using deterministic trends and the relative price of non-tradables to proxy for BS effects. The empirical results provide further support for the hypothesis that real exchange rates are well described by symmetric, nonlinear processes. Furthermore, the half-life of shocks in such models is found to be dramatically shorter than that obtained in linear models.

In two recent contributions Lothian and Taylor, and Cuddington and Liang, produced empirical evidence that annual data for the dollar-sterling real exchange rate spanning two centuries exhibited a non-linear deterministic trend. This trend could be proxying Harrod-Balassa-Samuelson effects. Lothian and Taylor showed that a linear stationary autoregressive mode, which embodied a cubic trend, implied much faster mean reversion of the real exchange rate to shocks than a model that excluded the trend. This article shows that both non-linearity and a deterministic trend can be allowed for in a theoretically appealing manner and that the fitted models provide a parsimonious explanation of both the dollar-sterling and franc-sterling real exchange rates over the two centuries of data. Generalized impulse response function analysis of the models demonstrates that the speed of adjustment to shocks can be even faster when trends are considered.

A new panel unit root by Chang (Journal of Econometrics, 110, 261-92, 2002) is employed on a set of financial ratios with a view to improving the power of unit root tests when applied to a relatively small number of observations (in the present case 38 annual observations). The test is innovative in that it allows for cross-sectional dependencies and the asymptotic distribution of the test is standard. Although standard Dickey-Fuller tests suggest that individual financial ratio series are nonstationary, panel unit root tests strongly reject the null hypothesis of a joint unit root in the ratios. Taken together the evidence from the proposed new analysis implies strong persistence in the ratios but that their characterization as I(1) processes may be misleading. These findings have important implications for accounting and finance researchers who employ financial ratios as explanatory variables.