Hallo! I have done a sample size calculation for proportions with EpiR. The input is: treatment group rate p=0.65 control group rate p=0.50 significance level 0.95 power 0.80 two-sided ration group 1 and 2: 1.0
I have done this in the following way: library(epiR) epi.studysize(treat = 0.65, control = 0.5, n = NA, sigma = NA, power = 0.80, r = 1, conf.level = 0.95, sided.test = 2, method = "proportions") Result: $n [1] 82 PASS 2002 and NQuery give both 170 subjects per group without continuity correction. With continuity correction 183 per group. Looking at http://statpages.org/proppowr.html I get 182 subjects per group (with continuity correction, I admit). What am I doing wrong? Can anybody explain this? Best wishes Karl ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
