A model composed of two (or more) submodels in which submodel A holds true in one set of circumstances, and submodel B in another (e.g., submodel A applies at time <I>t</I> if <I>Y<SUB>t-1</SUB></I> is greater than a specified value, submodel B if <I>Y<SUB>t-1</SUB></I> is less than that value). The purpose is to obtain accurate forecasts by using the most appropriate model for the situation.<o:p></o:p></P>