Exchange rate bubbles: Fundamental value estimation and rational expectations test

We propose a model of periodically collapsing bubbles which extends the Van Norden (1996) model, and nests it, by considering a non-linear specification for the bubble size in the survival regime, and the endogenous determination of the level of the fundamental value of the stochastic process. They allow us to test for rationality in the formation of expectations, and remove the arbitrariness of exogenously setting the level of the fundamental value. This general model is applied to the exchange rate of the Brazilian real to the US dollar from March 1999 to February 2011. The futures market exchange rate is used as a proxy of its expected future value, and three different structural models are considered for the determination of the fundamental value. The first two imply that the exchange rate satisfies either purchasing power parity (PPP), or a modified version of it. The third structural model is a version of the monetary model of exchange rate determination, fitted to the period under consideration. We obtain the maximum likelihood estimate of the parameters of the models, explore the properties of the errors, test its restricted versions, and compare the three specifications for the fundamental. We find that the models we propose fit well the data, and are useful in the heuristic interpretation of the exchange rate movements of the period. Finally we select the structural models that display the best performance, according to several criteria.