Annette Taylor wrote: > I don't think you can calculate power--I recall doing power calculations for my > dissertation--the last time I thought that was a good use of my time! But you > can certainly ask SPSS to calculate effect size, and that is, in my mind, a > sufficient approximation.
I don't understand how effect size is an approximation of power at all. Power is a funtion of two independent components: effects size and sample size (suitably adjusted depending on the design). Sample size alone tells you little about how the power of your test -- if the size was low, but the n was big, you may well have a powerful test; if the size was high but the n was quite small, you may not havea powerful test. There are detailed instructions and tables for calculating power for independent samples ANVOAs in David Howell's statistics textbook (the larger one, not _Fundamentals..._) as well as a few others (Jacob Cohen's own book, of course, among them). It is not all that difficult. This a perfect opportunity for your student to learn how to do it. Regards, -- Christopher D. Green Department of Psychology York University Toronto, Ontario, Canada M3J 1P3 e-mail: [EMAIL PROTECTED] phone: 416-736-5115 ext. 66164 fax: 416-736-5814 http://www.yorku.ca/christo/ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
