# Balanced repeated measures design

Okay this is my problem:

• I have 12 participants.
• Each participant spent 3 nights in my lab doing a reaction time task at four timepoints during the night(12, 1, 2 and 3 oclock), with one week between each of those nights.
• Each night, each participants was exposed to one of three experimental conditions, such that each participant completed each condition at the end of the three weeks, but with the order of conditions fully balanced over subjects.

So in the end I have for each participant, for each condition, four mean reaction times.

I wanted to use a linear mixed model with condition and timepoint during the night, and the interaction of condition*timepoint as fixed effects(since I expect reaction time to decrease less in one of the three conditions during the night). As a random effect I wanted to include subject, but I'm not confident of how I would be doing this in SPSS and whether a mixed model is the right way to go.

Can someone give me a few hints on how to proceed? I'd really appreciate it!

Unfortunately, it is not (yet) implemented in SPSS. But there are SAS macros. See how hld-f2.sas is used.
• Are you aware of an R implementation of this idea? – Henrik May 12 '15 at 13:09