Sample size calculation for Poisson regression

[BayzidurRahman]

Is there any easy way to calculate sample size for a Poisson model with offset? I am planning a cohort study with recurrence short term outcome. That is, one participant can get the outcome multiple times during the follow-up period.

[Mike_N]

I think the way to do this is to use PROC POWER with a CUSTOM statement. See this example: SAS Help Center: Logistic Regression Using the CUSTOM Statement. The linked example is for logistic regression, but you can adapt the approach for other generalized linear models, like a Poisson model. 

[Ksharp]

You also could check PROC GLMPOWER for the MIXED model.

[BayzidurRahman]

Hi, that looks like an easier option but I cannot find options to specify the Poisson model options such as, link=, offset=, dist= etc.