I struggling to understand whether it is possible to have random effect without the respectively fixed effect.
For example, I use
lme4 to fit two models:
y ~ 1 + (1 + x | z)
y ~ 1 + x + (1 + x | z)
the random effect for
x seems to be the same despite the fact that in the first model, there should be a random effect of
z on the slope of
x doesn't seem to have a fixed effect (!). What am I missing?