- The needed sample size is calculated to have 80% power to detect a common odds ratio of 2.7. POPF rates of 12% and 20% are assumed after PJ within the hard and soft pancreas stratum respectively (yielding 4.8% and 8.4% after PG). Note that, given the unequal size strata, this leads to an expected POPF rate of 16.8% after PJ and 7% after PG (≈12% POPF overall).