search for: bsamsiz

All, I have been digging around in the help files and found bsamsize in Hmisc, but I am wondering if i am using it right. So, here is the question: given a binomial response (success/failure) for 2 groups (treatment/control) and I want to estimate the necessary sample size (n) to determine if the magnitude of the difference between treatments and controls is...

...2-sample proprotion test. I have the hypotesized treatment probability of success (0.80), the hypotesized control probability of success (0.05), and also de proportion of the sample devoted to treated group (5%), (fraction=rho=0.05, n2/n1=19). Using the Hsmisc library, it seemss that I can use bsamsize (option 1) or samplesize.bin (option 2, alpha=0.05 or option 3 alpha=0.05/2, I am not sure after reading the help page) and I can use STATA (option 4). library(Hmisc) #OPTION 1: bsamsize(p1=0.8, p2=0.05, fraction=0.05, alpha=.05, power=.9) # n1 =2.09, n2=39.7, TOTAL=42 #OPTION 2: sample...

Hi, I'm try to compute the minimum sample size needed to have at least an 80% of power, with alpha=0.05. The problem is that empirical proportions are really small: 0.00154 in one case and 0.00234. These are the estimated failure proportion of two medical treatments. Thomas and Conlon (1992) suggested Fisher's exact test and proposed a computational method, which according to their table