Re: [R] Statistical Power
On Tue, 23 May 2006, Christopher Brown wrote: How can I compute a power analysis on a multi-factor within-subjects design? If you are capable of installing source packages and if you know what a general linear hypothesis test is, you can: download 'hpower' to your computer http://gd.tuwien.ac.at/languages/R/src/contrib/hpower_0.1-0.tar.gz and install it. Then library( hpower ) ?glhpwr should get you started. [ Part 3.28: Included Message ] Charles C. Berry(858) 534-2098 Dept of Family/Preventive Medicine E mailto:[EMAIL PROTECTED] UC San Diego http://biostat.ucsd.edu/~cberry/ La Jolla, San Diego 92093-0717 __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] Statistical Power
On Wed, 2006-05-24 at 09:22 -0700, Charles C. Berry wrote: On Tue, 23 May 2006, Christopher Brown wrote: How can I compute a power analysis on a multi-factor within-subjects design? If you are capable of installing source packages and if you know what a general linear hypothesis test is, you can: download 'hpower' to your computer http://gd.tuwien.ac.at/languages/R/src/contrib/hpower_0.1-0.tar.gz and install it. Then library( hpower ) ?glhpwr Downloading, unzipping the package on to FC4 running R 2.3.0 gives an error message about a bad description file when trying to install hpower. R CMD INSTALL hpower Rick B. __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] Statistical Power
On Wed, May 24, 2006 20:22, Rick Bilonick wrote: Downloading, unzipping the package on to FC4 running R 2.3.0 gives an error message about a bad description file when trying to install hpower. R CMD INSTALL hpower Indeed, it does so on both my Ubuntu and Win XP boxes. The problem is that the DESCRIPTION file does not have a proper Maintainer line. If you simply add the line: Maintainer: no-one [EMAIL PROTECTED] and follow the regular procedures, it should install. However, I am not so sure that this is the right thing to do with regards to permissions etc. Anyone any advice? Ioannis -- Ioannis C. Dimakos, Ph.D. University of Patras Department of Elementary Education Patras, GR-26500 GREECE http://www.elemedu.upatras.gr/dimakos/ http://yannishome.port5.com/ __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] Statistical Power
For other than the basic situations I generally use simulation to estimate power. Follow these basics steps: Write a function that takes as input the things that you may want to change in estimating power (sample size, effect size, standard deviations, ...). Inside the function generate random data based on the inputs and your study design and computes the p-value that you are interested in and returns that p-value. Then use the function replicate or sapply to run this function a bunch of times (I usually do about 1,000) and save the p-values in a vector. The estimated power is then mean(outvec 0.05) (or whatever your alpha level is). The website: http://maven.smith.edu/~nhorton/R/ has an example of simulating power for a mixed effects model (though it uses a loop rather than replicate). Hope this helps, -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare [EMAIL PROTECTED] (801) 408-8111 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Christopher Brown Sent: Tuesday, May 23, 2006 9:54 AM To: R-help@stat.math.ethz.ch Subject: [R] Statistical Power How can I compute a power analysis on a multi-factor within-subjects design? __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
