The data file I have is quite large, over thousands of entries. When I ran the PROC FREQ command you suggested, I first looked at the dependent variable I'm using in the mixed model, "Bout_length". It returned a level of 668 The explanatory variables I use in the mixed model are rep, sex, and line, which are just 2, 2, and 3 levels respectively. I normally will use the PROC SQL feature to separate it out into a sheet for a single line and its control, which I then run the mixed model on.
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