Hallo! Does anybody know what epiR calculates with method = "survival"? library(epiR) library(survival) epi.studysize(treat = .65, control = .50, n = NA, sigma = NA, power = 0.80, r = 1, conf.level = 0.95, sided.test = 2, method = "survival") Because I found out that method "proportion" does not do what I admitted, I am somehow careful with the examples.... ? Thanks! Karl