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A constant linear decrease doesn't not mean A>B>C>D>E; rather on average there is a constant decrease across time. If you want the stated equation, then you need to form a conjunction. Typically, a constant linear decrease for 5 repetitions would be defined as 2 1 0 -1 -2. The caveat is that this contrast could be driven by A and E, but it would still be considered linear across time. Hope this helps. Best Regards, Donald McLaren ================= D.G. McLaren, Ph.D. Postdoctoral Research Fellow, GRECC, Bedford VA Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School Office: (773) 406-2464 ===================== This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended only for the use of the individual or entity named above. If the reader of the e-mail is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that you are in possession of confidential and privileged information. Any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this e-mail unintentionally, please immediately notify the sender via telephone at (773) 406-2464 or email. On Thu, Jan 20, 2011 at 11:55 PM, Gelareh Ahmadi <[log in to unmask]> wrote: > Dear FSL experts, > > My question is about designing GLM for repeated measure ANOVA. > > I have FA images from DTI scans for my subjcets. Each subject scanned in 5 different time points. > > I want to design a GLM which shows areas with decreased FA between time point 1&2, 2&3, 3 &4 , 4&5 and also areas which shows linear decrease from time point 1 to time point 5. > > I think for my first goal I should use ANOVA (1 factor-5 level), therefore for instance, for 2 subjects having scan in 5 time points, in order to show decrease FA between timepoint A&B, B&C, C&D and D&E, I should design: > > Group EV1 EV2 EV3 EV4 EV5 EV6 EV7 > subj1 subj2 time1 time 2 time 3 time 4 time5 > 1 1 0 1 0 0 0 0 > 1 0 1 1 0 0 0 0 > 1 1 0 0 1 0 0 0 > 1 0 1 0 1 0 0 0 > 1 1 0 0 0 1 0 0 > 1 0 1 0 0 1 0 0 > 1 1 0 0 0 0 1 0 > 1 0 1 0 0 0 1 0 > 1 1 0 0 0 0 0 1 > 1 0 1 0 0 0 0 1 > > Contrasts EV1 EV2 EV3 EV4 EV5 EV6 EV7 > A-B 0 0 1 -1 0 0 0 ( shows decrease FA between timepoint 1&2) > B-C 0 0 0 1 -1 0 0 > C-D 0 0 0 0 1 -1 0 > D-E 0 0 0 0 0 1 -1 > > But I have no idea how I can show there is constant linear decrease from time point 1 to timepoint 5 ? I mean showing that FA1>FA2>FA3>FA4>FA5. > > I would highly appreciate if any one could let me know if Iam correct for the first goal and how I can solve my second problem. > > Best Regards, > > Gelareh >