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From | Scott Baldwin <baldwinlist@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: Computing effect size for a clustered randomized control trial |
Date | Mon, 3 May 2010 19:08:31 -0600 |
I'm not aware of any built in or user-written method in Stata for computing power in cluster randomized trials. You can try the Optimal Design software (http://sitemaker.umich.edu/group-based/optimal_design_software) or the formulae in David Murray's book "Design and analysis of group randomized trials." Best, Scott On Mon, May 3, 2010 at 5:23 PM, Joe McCrary <joe.mccrary@gmail.com> wrote: > I am designing a randomized control trial, where we are going to > select about 12 students per classroom and randomize them into 3 > groups, a control and 2 treatment groups. Is there a way I can compute > the number of classrooms needed for the study using the following > criteria: > > Desired power=0.8 > Estimated effect size = 0.2 > alpha = 0.0167 > 1 pre-test measure > 1 post-test measure > approx correlation between the two measures = 0.25 > > -- > Joe McCrary > Senior Research Associate > WestEd-Atlanta > 260 Peachtree St., Suite 2200 > Atlanta, GA 30303 > > ph: 541-782-8626 > fax: 404-393-3797 > > Skype: joe.mccrary > Google talk; joe.mccrary > ********************** > > "No problem can be solved from the same level of consciousness that created it." > --Albert Einstein > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/