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Caroline, This looks reasonable, although I would have an EV for Group as you want both main effects in the model with the interaction - or so I was taught in my statistics class. Best Regards, Donald McLaren ================= D.G. McLaren, Ph.D. Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School Postdoctoral Research Fellow, GRECC, Bedford VA Website: http://www.martinos.org/~mclaren 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, Jun 27, 2013 at 4:26 PM, Caroline Montojo <[log in to unmask]> wrote: > Dear FSL experts, > > We would like to run a 2x2 Mixed ANOVA with Factor 1: Time (Pre- vs Post- > treatment; within-subjects factor) and Factor 2: Group (Medication vs > Placebo; between-subjects factor). We are interested in testing whether > there is a GroupxTime interaction (e.g., a differential change in the > medicated group). We set up on 2x2 Mixed ANOVA model following the guide > on the FSL website. > > We would just like to check that we setup up our interaction model > correctly. This is an excerpt from our 2x2 Mixed ANOVA design: > > Group EV1 EV2 EV3 EV4 EV5 EV6 EV7 … > Run GxRun Subj1 Subj2 Subj3 Subj4 Subj5 > 1 -1 -1 1 0 0 0 > 0 > 1 1 1 1 0 0 0 > 0 > 1 -1 1 0 1 0 0 > 0 > 1 1 -1 0 1 0 0 > 0 > 1 -1 -1 0 0 1 0 > 0 > 1 1 1 0 0 1 0 > 0 > 1 -1 -1 0 0 0 1 > 0 > 1 1 1 0 0 0 1 > 0 > 1 -1 1 0 0 0 0 > 1 > 1 1 -1 0 0 0 0 > 1 … > > Where EV1 Run is determined by Pre- (-1) vs Post (1) and the Interaction > terms GxRun is determined by the subjects' inclusion in the Placebo (Run > coding x1) or Medication ( Run coding x-1) group. Does this model setup > look reasonable to test the interaction effect? > > Thank you, > Caroline >