Hello, I am a novice to program R and have been trying to perform a repeated measures ANCOVA with Temperature as the dependent variable, Site as the independent variable, Date as the covariate and Year as the repeated measures. My dataset consists of temperatures from 4 sites, over 20 days, during 2 different years. There appears to be a significant effect of site, date and year on temperature, but no significant interaction between site and year or site and date. I originally performed two separate ANCOVAs, but my coauthor wants them in a single model. As far as I can tell, there is no simple way to do a repeated measures ANCOVA as there is for ANOVA. I have tried using: lm(formula = Temp~Site*Date + Year) , but wouldn't this just put year as an interaction that doesn't affect the model? Any help you can provide would be GREATLY appreciated!! -Carrie -- View this message in context: http://r.789695.n4.nabble.com/Repeated-Measures-ANCOVA-tp4114408p4114408.html Sent from the R help mailing list archive at Nabble.com.