>-----Original Message----- >From: Traci Giuliano [mailto:[EMAIL PROTECTED]
>The scheme works out so that each 1/4 of the participants sees two >profiles as follows (with half of each seeing the two profiles in >reverse order): >1A, 2A, 3A --> 1B, 2B, 3B >1A, 2B, 3A --> 1B, 2A, 3B >1B, 2B, 3A --> 1A, 2A, 3B >1B, 2A, 3A --> 1A, 2B, 3B > >My questions are as follows: > >1) What kind of design is this? How would I describe it? It's not >really completely between-subjects and not really within-subjects >either. The within-subjects element is really by condition rather >than variable. It looks like a 2 x 2 x 2 with repeated measures on the last variable. The repeated-measures (or within-subjects) variable is condition 3(with values A and B). > >2) How would/could I analyze this? Is there any way to take advantage >of the shared variance of having the same subjects be in >complementary conditions? If not, is it wrong to analyze this as a >completely between-subjects design (essentially treating each >participant's responses to the second scenario as if it came from a >different person)? I'm not well versed in all the issues/assumptions >here about how to partition the variance. If you have 16 subjects per condition, the sources and df would be: Between Subjects df = 63 (1) df = 1 (2) df = 1 (1 x 2) df =1 error (between) df = 60 Within Subjects df = 64 (3) df = 1 (1 x 3) df = 1 (2 x 3) df =1 (1 x 2 x 3) df = 1 error (within) df = 60 TOTAL df = 127 > >3) Given these issues, would you recommend that I just simplify >things by running this as a completely between-subjects design? >Typically, the benefits of a within-subjects design are a) more power >and b) fewer subjects. I seem to be getting b but not a here, and I >suppose I run a slight risk of sensitizing subjects. Given the >analysis problem, would it be more prudent to just run twice as many >subjects here and not deal with this mess? :-) You could counterbalance the order. ************************************************* Michael T. Scoles, Ph.D. Director, Arkansas Charter School Resource Center Associate Professor of Psychology & Counseling University of Central Arkansas Conway, AR 72035 voice: (501) 450-5418 fax: (501) 450-5424 ************************************************* --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
