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I have a mixed effects model with one random effect and two fixed effects, both of which are of interest. There is some reason to believe that there would be an interaction between these two fixed effects.
When I run the model with both main effects and their interaction, none of them are significant. If I take out the interaction term (which I probably shouldn't have done, but I did out of curiosity), one of the effects becomes (very) significant, in a way that would be of considerable interest. It seems to me that I should go with the model with the interaction in it, but I am concerned that I am missing the effect of the variable that becomes very significant once the interaction is removed.
Should I include the interaction in the model? If I haven't provided enough information here for someone else to give accurate advice, what should I consider in order to make this decision?
(Also this is my first question, so apologies if I have asked it poorly)