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| From | Joe McCrary <joe.mccrary@gmail.com> |
| To | Statalist <statalist@hsphsun2.harvard.edu> |
| Subject | st: Computing effect size for a clustered randomized control trial |
| Date | Mon, 3 May 2010 17:23:12 -0600 |
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/