just a quick question regarding main effects and interaction effects:

For example, in a LME model like

lme_model <- lmer(outcome ~ Group*Time + var1 + (1|Sub), data=datatable 

In the analysis there would be main effects of group, time (and var1), correct? Group x Time (or Group:Time , does it matter how I write it btw?) would then be called an interaction effect, if I am not mistaken? Someone told me that main effects are without direction. Is that correct? I am pretty sure I am getting I direction shown in the output of summary(lme_model). The interaction effect also has a direction effect, hasn't it?

Maybe the other person used anova(lme_model) to get to that opinion, which instead of summary(lme_model) doesn't produce estimates and a direction for main and interaction effects?

just a quick question regarding main effects and interaction effects:

For example, in a LME model like

lme_model <- lmer(outcome ~ Group*Time + var1 + (1|Sub), data=datatable 

In the analysis there would be main effects of group, time (and var1), correct? Group x Time (or Group:Time , does it matter how I write it btw?) would then be called an interaction effect, if I am not mistaken? Someone told me that main effects are without direction. Is that correct? I am pretty sure I am getting I direction shown in the output of summary(lme_model). The interaction effect also has a direction effect, hasn't it?

Maybe the other person used anova(lme_model) to get to that opinion, which instead of summary(lme_model) doesn't produce estimates and a direction for main and interaction effects?

Edit: with direction I meant positive or negative, e.g. there is a negative groupXtime interaction effect