Hello, Thank you for the response! I will certainly check out the recommended book. I was wondering if my original code incorrect? Can you explain why? I was using the code I found in this article online: Paper 188-29 Repeated Measures Modeling With PROC MIXED E. Barry Moser, Louisiana State University, Baton Rouge, LA I attempted to run the proc Glimmix code you suggested but the log is telling me I'm missing a parentheses; I attempted to add one in the plots statement: but it didn't work. Then I attempted to remove this line completely and it also didn't run. I'm wondering why you did not include "lights" within the random statement here? The assumptions you made are correct, except that I have more than 2 levels of "trial_type" (there are actually 5). Each male was exposed to each trial type twice and within each trial type there are two measurements taken--one before and one before the variable "lights" so that there are two levels of lights. Thank you so much.
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