Thanks Rick and LVM for your answers! To be more precise: We would like to determine the sample size for a study according to the primary study outcome which is a count variable. According to litterature, we know that the average number is 7 events in the population. We estimate a decrease of 20% in the treated group at the end of the study. With an expected rate of 7 events using a two-sided Poisson regression at the 5% alpha-level, what is the number of subjects needed to detect a 20% decrease with at least 80% power? Thanking you in advance for your help! Best
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