topic Re: Sample size calculation crossover design in Statistical Procedures

Sample size calculation crossover design

ANKH1 — Tue, 09 Apr 2019 21:12:11 GMT

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!

Re: Sample size calculation crossover design

sld — Tue, 16 Apr 2019 20:46:41 GMT

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.

Re: Sample size calculation crossover design

ANKH1 — Tue, 07 May 2019 16:19:52 GMT

Thanks. Although a good read it doesn't address power calculation for crossover designs. Is there another article you recommend that addresses this calculation?

Re: Sample size calculation crossover design

sld — Tue, 07 May 2019 18:09:19 GMT

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.