Simple Effects within MLM Question

[r2theoozbeck]

Hello,

I have a brief question about "simple effects".

I ran a Mixed Model with an interaction effect, then I made a simple effects table based on the moderator results within the Mixed Model.

How come the moderator fixed effect in the Mixed Model shows one level of significance (P=.002) while the simple effects model, the moderator effect at different levels (mean, Mean +/- 1 SD) shows a different level of significance (P<.001)?

Maybe I am confused in a broader sense, what does the simple effects function within Mixed Model results actually show? What is the difference between simple effects and fixed effects?

Thank you very much, please let me know if I can clarify my question further!

Jamovi is wonderful,
-Rouzbeh

[mcfanda@gmail.com]

Fixed effects are all the effects in the model that are not random. Simple effects are the (fixed) effects of one independent variable estimated at different levels of a moderator. For instance, if you have a model with x and groups as independent variables, the simple effects of x are estimated for each group defined by group variable.

When there is an interaction between the independent variables, the simple effects are different among themselves, and therefore their t-test and p-values will be different.