Hi, I am having an issue debating whether to include an interaction treatment in my random statement.  I ran an animal trial 3 times (due to lack of space for housing more animals).  So I had 3 repetitions of animals.  There were 3 treatments within each repetition and 5 animals per treatment.  So 15 total animals that we measure weight (and other things) weekly per repetition.  What I didn't expect was that each repetition is significantly different from each other.  So I included repetition as a random statement (along with repeated week/subject=animal).  Since the rep is different and the treatments are affected by rep, should I also include repetition*treatment within the random statement?  If I run rep*treatment within the model statement as a fixed effect, it is not significant.  Any insight would be much appreciated....I'm very unsure as to what to do.  Thanks in advance to everyone for your time!! Sylvia ... View more