The ARDL bounds test of Pesaran, Shin and Smith (2001) has become an important tool for exploring cointegration. However, some pretesting is needed for its valid application: regressor variables should not be integrated of order higher than unity; the dependent variable must be integrated of order one; and that there be at most one cointegrating equilibrium involving the dependent variable, where only the dependent variable, and not the regressors, responds to deviations from this equilibrium.
