I have conducted both, a moderated multiple regression analysis and a two-way ANOVA (spliting each predictor at its median), obtaining different results. Using the two-way ANOVA, the interaction term (Z x X) was significant (p = .29), whereas using the moderated regression analysis the interaction term was non-significant (p = .183). Main effects (Z and X) are signiifcant with both procedures (p < .01). Analysis were conducted with SPSS. Sample size: n = 100.

In performing the moderated regression analysis with SPSS, I first center de predictors to create the product term: (Z - mean of Z) * (X - mean of X). Then I carry out a stepwise regression analysis entering both predictors and the product term as independent variables: Z, X and Z x X; and Y as the dependent variable.

Is there anything wrong? Could someone explain me these differences? Any suggestion to continue with the analysis?

Thank you all in advance.