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Hello,
We are designing a cross-over repeated measures design. Participants will have all 4 treatments at four different sessions days. During each session, samples will be collected over several time points for 2 hrs. There will be a washout period between sessions.
Is there a SAS procedure for such calculation?
Thank you!
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You can use the GLIMMIX procedure for this purpose. See PROC GLIMMIX as a Teaching and Planning Tool for Experiment Design.
I hope this helps.
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Thanks. Although a good read it doesn't address power calculation for crossover designs. Is there another article you recommend that addresses this calculation?
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The design planning process described in Stroup's paper works for any statistical model that you can specify using either the MIXED or GLIMMIX procedures. So if you can write a statistical model for your crossover design, then you can estimate sample sizes for specified exemplary datasets. That's the beauty of this approach: it can deal with a wide variety and complexity of statistical models. Although, of course, the process gets more involved as the statistical model gets more complex.
I do not know of any papers describing this process for a crossover design, but that does not mean that there are none. I suggest starting simply, with "subsets" of your design--for example, an assessment of sample size for just the first period if you have replicate subjects--and then build from there.
I hope this helps.