I am trying to run an lmer model with by-participant and by-item random intercepts. My dataframe has 1920 rows in total. The number of items is 32 and the number of participants is 60 (32 * 60 = 1920). When I run an lmer using the lmerTest package, however, I get the following results.
Number of obs: 1824, groups: participant_id, 57; stimuli_presented, 32
I have checked the levels of my participant_id and it is 60. Why are my 3 participants disappearing? Does this kind of thing happen at all? The following is my code.
data$stimuli_presented <- as.factor(data$stimuli_presented) # 60 levels data$participant_id <- as.factor(data$participant_id) # 32 levels model <- lmer(dv ~ iv1 + iv2 + iv3 + iv4 + iv5 + iv6 + iv7 + (1|participant_id) +(1|stimuli_presented), data=data)
Thanks a lot!