ARE EXCHANGE RATES PREDICTABLE?: MARKOV SWITCHING MODEL WITH ENDOGENOUS TRANSITION PROBABILITIES

다국어 초록 (Multilingual Abstract)

The Markov switching model (MSM) is considered interesting because it captures nonlinearity and structural instability of economic time series subject to occasional regime shifts. Engel and Hamilton (1990) apply a MSM in an exchange rate analysis using a constant transition probability function. That is, they assume that the probability of switching from on state to the other is constant regardless of the status of the economy. However, the likelihood of government intervention or regulation-the main causes of regime changes - usually is not independent of a country's economic status. This paper proposes a nonstationary MSM, in the sense that the transition probability function is time varying and a function of market fundamentals. This specification emphasized the role of real interest rate differentials in determining the direction of exchange rate movements. This paper develops maximum likelihood estimation procedures for four different specifications of endogenous transition probability function, - constant, linear, step, and logit-using the EM algorithm. Nonstationary MSM's are estimated using quarterly data of the pound-dollar exchange rate from 1974 to 1989. Forecasting results show that nonstationary MSM's outperform the constant transition probability model as well as the random walk model. For out-of-sample forecasting, nonstationary MSM'S outperform the random walk model, while Engel-Hamilton model does not. The results provide strong support for the nonstationary MSM; i.e., the exchange rate follows a switching-regime stochastic process which is driven by the real interest rate differential.