Rich Ulrich <[EMAIL PROTECTED]> wrote in article = <[EMAIL PROTECTED]>... > - what to do - > Approximate your design and power calculation with > the nearest, likely, paired t-test. >=20 > Or, look at the contrast of interest, and compute > the power based on the simple ANOVA on the contrast; > you probably want to dummy up some data for this,=20 > if you don't have good pilot data on hand.
Definitely reccommended for beginners. > Having said that, I will say that you should probably > not use any power analysis program that does not > have ample documentation, including sample problems -- > plug in numbers to match previous results, > and match (with *some* accuracy) your design. I'd suggest GPower as there is some documentation out there and it is = free. > The problem has been asked before, of course. > I don't remember being impressed by Repeated Measures > reported (even) for expensive programs, though there=20 > was a recommendation or two (I think I recall). The problem with repeateed measures seems to be estimating the additional parameter(s). Unless you have good sources for estimates (e.g., pilot data) it will involve a lot more hand-waving than independent measures. Thom . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
