05-22-2012 06:47 AM
I would like to calculate the sample size in a study : crossover Williams design (3 treatments and 6 sequences). I only find the following page on the web but it only gives information about the simple 2X2 crossover design using PROC POWER (and PAIREDMEANS statement).
Do you have any idea?
Thanking you in advancesa
05-22-2012 08:06 AM
I think you might have to sneak up on this one. Use PROC MIXED to calculate non-central F values for a range of sample sizes and expected effects, and see which one best approximates the power desired. See Chapter 12 in Littel et al.'s SAS for Mixed Models, 2nd. ed., and expand from there.