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Hi Donald, Not sure if I follow your suggestion either. If gender is a degenerate regressor in a repeated measures design, then isn't the interaction of gender with any other factors degenerate as well? cheers, -MH On Thu, 2011-05-12 at 19:56 +0200, Alexander Olsen wrote: > Thanks for your suggestion Donald. How would you go about to set up the > design martrix (in FEAT) in this case? > > > MCLAREN, Donald wrote: > > I'd agree on the age part since its likely everyone is a different > > age; however, I'd add gender as a covariate and make it interact with > > the repeated measure (essentially coding it as the covariate and also > > as the covariate*each measure). This would allow you to investigate > > any gender*measure interactions. > > > > 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, May 12, 2011 at 1:44 PM, Alexander Olsen > > <[log in to unmask] <mailto:[log in to unmask]>> wrote: > > > > Hi Michael, > > Thank you so much for helping me. So that means that I should set > > up the design matrices without any covariates for age and gender? > > > > cheers, > > Alexander > > > > > > > > Michael Harms wrote: > > > > Hi Alexander, > > Given that you are modeling the mean of each subject using a > > repeated > > measures design, that mean already incorporates that subject's > > age and > > gender as part of its estimate. That is, if you added EVs for age > > and/or gender, those EVs can be represented as a linear > > combination of > > the columns modeling each subject's overall mean, and thus you > > would get > > a degenerate design matrix. (This wouldn't strictly be true > > for age IF > > the value you used for age differed across the repeated scans of a > > subject, but unless your scans were spaced far apart > > temporally, you > > still might get a poorly conditioned design matrix). > > > > cheers, > > -MH > > > > On Thu, 2011-05-12 at 01:12 +0100, Alexander Olsen wrote: > > > > > > Dear FLS experts, I'm struggling a bit with setting up my > > analysis. What I would like to do is a repeated measures > > design with four timepoints, as in this example: > > http://www.fmrib.ox.ac.uk/fsl/feat5/detail.html#ANOVA1factor4levelsRepeatedMeasures > > > > However, I would also like to add age and gender as > > covariates in order to "remove" these effects. I hope > > anyone can help me, or direct me to an example which > > describes this. > > Thank you so much in advance. > > Alexander > > > > > >