Hi Andy, If you could provide a sample data set, it would help others to give a solution.
I suggest look at the data and select a model, then anova. Take group as one variable, record time (1 to 24 ) as the second variable and the week day (Monday to Friday) as the third variable. Then test the interaction between three variables at first. I hope the following code helps. df <- data.frame(value = rnorm(24*5*5), group = rep(1:5,5*24), time = rep(1:24,each=5), day = rep(c("M","T","W","R","F"),each=24)) anova(lm(value ~ group*time*day,data=df),lm(value ~ group*time*day-group:time:day,data=df)) ----- A R learner. -- View this message in context: http://r.789695.n4.nabble.com/periodic-time-series-tp3062866p3062908.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.