simple-effects analysis
when an analysis of variance or multiple regression analysis has identified an interaction effect among two independent variables, an examination of the effect of one variable at one level of the other variable. For example, if there were two levels of a factor, a1 and a2, and two levels of a second factor, b1 and b2, the comparison of a1 versus a2 at b1 would represent one simple-effects analysis; another would be a comparison of a1 versus a2 at b2. In this way, a series of simple-effects analyses can be used to break down an interaction into its component parts.