I want to perform power calculations for an RCT, and do this not only for the whole sample but also for the expected heterogeneity tests. Does anybody know literature on how to perform power calculations for subgroups?
For everyone who comes across the same question, I have found the online tool PowerUp! (https://www.causalevaluation.org/power-analysis.html) which provides analytic formulas to calculate power in the case of moderator analysis and also links to background papers.
Many thanks to the co-principal investigators Nianbo Dong, Benjamin Kelcey, Jessaca Spybrook, and Rebecca Maynard for making these resources available!