I have a 2 by 2 design with 12 subjects. The two factors are within-subjects variables. For each cell, 24 responses were collected from each subject. My question is whether I need to aggregate every 24 responses into a mean and then use the mean in lmer as the dependent variable. This webpage http://talklab.psy.gla.ac.uk/simgen/faq.html seems to suggest that aggregation is not needed if use mixed effects model, but I doubt that it is true.
Also, if the responses are binary responses, can I just average them and use generalized lmer with binomial family?