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Hi! I am once again running some moderation models and in addition to moderation I am interested in simple main effects. On the output I get the coefficients for the product term and its components. I am wondering if the coefficient for components gives the simple main effects or if I need to run separate analysis for this. In other words, I have: COND MDD CONDXMDD Does the coefficient for COND gives the simple main effect for that variable or is that coefficient "conditional." I ask because when I run simple main effects outside of the context of interaction (aka in separate runs for COND and MDD), I get different mean difference or coefficients for COND and MDD. I hope I am clear in what I am asking. Thanks very much. 


When you include the main effects and the interaction, the regression coefficients are partial regression coefficients as they should be. 


What do you mean by partial regression coefficients as they should be? If I wanted to report the main effects, do I report these partial ones? Or do I run the model again without the interaction? I ask because the coefficients are different in the two runs and I just don't know which output to report the main effects from. If I use the coefficients from the interaction model the partial coefficient stay significant after i apply the Holm modified Bonferroni to correct for experiment wise error because I am running multiple tests. But I run it without the interaction  by looking at simple main effects at each level of the moderator variable then the effect is no longer significant when I apply the Holm modified Bonferonni. 


You report the coefficients from the model that includes both the main effects and the interaction. 


Thank you. Please help me with one more thing. I received the answer below in response to a question I posed regarding moderation. At the time, I thought I "got it" but I'm afraid I'm not certain I am doing this correctly. Esentially, I have 3 regression paths. COND (treatment condition  dummy coded 0 1  0=group; 1=family) MDD (presence of depressive disorders  dummy coded 0 1  0=absent; 1 = present) COND X MDD (the interaction). I did X  0 = Interaction for GROUP = 0 and MDD = 0. I then replaced X in the equation and got what I think it is the mean for GROUP and MDD present. I don't know how to get the means for FAMILY AND MDD PRESENT AND FAMILY AND MDD ABSENT. You don't need 4 runs  you have all the estimates you need in the run with the interaction. You just combine the estimates in 4 different ways in line with regular dummy variable regression:  the intercept gives the mean when both dummies (and therefore their interaction) are zero  the intercept plus one slope gives the mean for the cells where you have 0, 1 or 1,0  the intercept plus both means gives you the mean for the cell where both dummies, and therefore their interaction, are 1. 


I don't know what to add where in order to get "the intercept plus one slope gives the mean for the cells where you have 0, 1 or 1,0" 


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