The documentation of
effects package says
"If asked, the effect function will compute effects for terms that have higher-order relatives in the model, averaging over those terms (which rarely makes sense)"
My question is why does it rarely make sense? What if we have a mixed model like
y ~ f1*f2*f3 + (1|sub) and only the
f1:f2 interaction is significant? Isn't it reasonable to ignore the 3-way interaction and look at the simpler (and significant) 2-way interaction(s)?