Testing for short-run threshold effects in a vector error-correction framework: a reappraisal of the stability of the US money demand

Abstract

In this paper we analyze the stability of the money demand system in the US. To this aim, we develop an estimation and testing framework for a threshold vector error-correction model (VECM), where short-run dynamics are regime dependent and are driven by an exogenous, stationary and ergodic threshold variable. We modify a traditional Wald-type test for linearity and derive its asymptotic distribution, which turns out to be non-standard, but similar to the one proposed by Andrews [Andrews, D. 1993. “Tests for Parameter Instability and Structural Change with Unknown Change Point.”