Dennis, There are many types of contrasts that are possible within the repeated measures design. The type of contrast you seem to be dealing with is polynomial which examines whether there is a polynomial trend (across the categories). Typically, you can report contrasts between two groups using the F or t-test since both will provide you with the same p-value at this level of analysis.
Do you have a reason to believe that the effect you are looking at is polynomial (i.e. quadratic, cubic, ect)? More specifically, does a 4th order effect help to explain the "task" you are describing? I generally do not report the contrasts unless it is theoretically substantive. If it is not important to your understanding of the phenomena then I would just report the within-subjects effect. I hope this helps. I just joined the listserv and your e-mail was the first e-mail I received so I hope my reply is appropriate. Sincerely, Jeff Dang --------------------------------------------------------------- Jeff Dang, MPH Statistician UCLA Cousins Center for Psychoneuroimmunology (Affiliated with the Neuropsychiatric Institute and Department of Psychiatry and Biobehavioral Sciences) 300 UCLA Medical Plaza, Room 3148 Los Angeles, CA 90095-7057 Tel: 310-267-4389 Fax: 310-794-9247 E-mail: [EMAIL PROTECTED] Web: http://www.cousinspni.org/ ATTENTION The information contained in this message may be legally privileged and confidential. It is intended to be read only by the individual or entity to whom it is addressed or by their designee. If the reader of this message is not the intended recipient, you are on notice that any distribution of this message, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and delete or destroy any copy of this message. -----Original Message----- From: Dennis [mailto:[EMAIL PROTECTED] Sent: Saturday, January 24, 2004 6:07 AM To: [EMAIL PROTECTED] Subject: [edstat] SPSS repeated measures: reporting within subjects effects Dear all I have to report within-subjects effects of the results of my repeated measures design. My within subjects IV is 'TASK', has 5 levels. 1. Shall I report the results as F statistics 2. I have sometimes significance in within subject contrasts. How can I call them so a reader would get the idea. I don't particularly like 'contrasts'. Example. There was significant main effect in the within-subjects variable TASK, F(1, 4) = 3.083, p = 0.018, which is has significant in the 4th order contracts, F(1,1) = 5.997, p = 0.019. Thanks a lot Dennis A http://www.ipo.tue.nl/homepages/dabrazhe/ps/ . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . ================================================================= . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
