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Hi Jan. Thanks for the quick response. No, I am using the GUI and I do have the latest updates. I did look at the code, and it seems to me that it is hard coded to look for 4 columns, but maybe I'm missing something? Thanks. -John -----Original Message----- From: Jan Gläscher [mailto:[log in to unmask]] Sent: Friday, October 31, 2008 4:35 PM To: West, John D. Cc: [log in to unmask] Subject: Re: [SPM] Flexible factorial design error Hi John, are you using the GUI to define your factors or do you specify SPM.xX.I directly? (The instructions in the manual are for entering the condition number via the GUI.) Also, make sure you have the latest upgrades installed. Let me know if the problem persists. Best, Jan West, John D. wrote: > Hello. > > I am following Glascher and Gitelman's guide for flexible factorial design and have run into a snag. > > I am trying to set up a 3x3 factorial design where I have three groups and three time points. I want to include the main effects of subject, group, time and groupxtime interaction. > > So I set up factors for subject, group, time and choose to specify all scans and factor matrix. > > I have input the subjects list in order of group then time. Therefore my factor matrix should be (since the subject factor does not have to be specified as it is a special factor): > > Group 1: > 1 1 > 1 2 > 1 3 > 1 1 > 1 2 > 1 3 > Etc. > > Group 2: > 2 1 > 2 2 > 2 3 > 2 1 > 2 2 > 2 3 > Etc. > > Group 3: > 3 1 > 3 2 > Etc. > > Then I set three main effects for subject, group, and time, and the interaction of group x time. > > This seems to be the right way to set things up but when I go to run this and create the design matrix I get the following: > Error: factor matrix must have four columns. > > I am not sure why I get this error as I should not need four columns (I only have three factors overall and the subject factor should not need to be set). Can anybody tell me where I might be going wrong? > > Thanks in advance for the help! > -John West > IU School of Medicine > -- Jan Gläscher, Ph.D. Div. Humanities & Social Sciences +1 (626) 395-3898 (office) Caltech, Broad Center, M/C 114-96 +1 (626) 395-2000 (fax) 1200 E. California Blvd [log in to unmask] Pasadena, CA 91125