search for: 2p2n

Hi, I am trying to do a power calculation for a difference in proportions test where I want to estimate the sample size required. I know (well estimate) that group one (n1) is 10% of the population and group 2 (n2) is 90% of the population. I know the effect size (h). pwr.2p2n.test only allows one variable to be left null whereas I would like both n1 and n2 to be determined where I know there relative proportions. Any ideas how to do this? Is there a different function? Thanks Dan -- ************************************************************** Daniel Brewer, Ph.D...

...tore counts and column proportions > xT<-x[,"True"] > xF<-x[,"False"] > yT<-x[,"True"]/colSums(x) > yF<-x[,"False"]/colSums(x) check length for dynamic looping > length(yT) [1] 8 now create loop > for(i in 1:length(yT)){ + pwr.2p2n.test(2*(asin(sqrt(yT[i]))-asin(sqrt(yF[i]))),n1=xT[i],n2=xF[i]) + } Error in pwr.2p2n.test(2 * (asin(sqrt(yT[i])) - asin(sqrt(yF[i]))), n1 = xT[i], : number of observations in the first group must be at least 2 this confuses me as if i enter the data as values the procedure works? Thanks in ad...

Hi All, I have a table based on ordial data and i want to compare proportions and i've seen in the pwr package i can use power.prop.test however i want to find out what the sig. value is based on n1,n2,p1,p2 and this package doesn't contain this.. Does anyone know of a package that does or is it a case of writting a function specifically for this? Many thanks in advance [[alternative

Hi all, I'm having trouble getting access to the pwr. This is on Ubuntu Lucid Lynx, 64 bit. I'm installing pwr via packages.install('pwr'), and loading it via library(pwr), both of which appear successful. Strangely, I never get access to the pwr object in R. I tried installing it to /usr/local/lib/R/site-library and ~/R/x86_64-pc-linux-gnu-library. I also tried installing it