Significant two-way interaction, but simple slopes are n.s.

Hi everyone,

I've seen similar questions like mine posted here before, but none of the replies were ever clear enough, so here's my Q. Thanks in advance. :)

I conducted a a variety of simple and multiple regression analyses with two predictors (IV1 and two dummy codes for IV2). So, the complete "steps" of the analyses I have conducted are as follows:

Model 1: IV1 predicts DV
Model 2: Dummy1 and Dummy 2 predict DV
Model 3: IV1, Dummy1 and Dummy 2 are now in same model, plus all interaction terms (IV1 x Dummy1, IV1 x Dummy2)

In Model 3, one of the two-way interaction terms (IV1 x Dummy1) is significant. Visually, it is a cross-over interaction. However, neither of the simple slopes are significant, so I am wondering how to interpret this data. Thanks in advance!


Omega Contributor
You keep the basic main effects in the model, but ignore interpreting them (they are conditional on an interaction). So focus on presenting and interpreting the interaction terms.