I would like to fit a 3-level hierarchical regression in lmer, however, I don't know how to specify the grouping factor above the second level. the model would be:
lmer(depedent ~ independent 1 + independent2 + (1|group1)....
And I would like to specify another group nested within
(1|group1/group2) but this gives an error message and group1:group2 is an interaction.
I've also tried separately
(1|group1) + (1|group2) but i'm not sure if this is correct.