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Dear FSL-experts, I am currently trying to do an analysis using FSL FIRST. I followed the recommendations of the UserGuide respectively the mailing list. However, I am not sure whether I set up the design matrices/contrasts correctly and would really appreciated it if you could take a look at them: 1. to analyze shape differences between a patient and a control group (EV1), controlling for age (EV2), sex (EV3) and IQ (EV4, using scores from Raven's Progressive Matrices) the matrix/contrast of the attached file shape.fsf was used. I did not demean the EVs, since I used the –D option of randomise 2. to analyze a correlation (EV1), again controlling for age, sex and IQ the matrix/contrast of the attached file corr.fsf was used. Again scores were not demeaned. Are these correct? Besides it would be really great, if you could answer the following questions: - setting up the design matrix, I was confused that group was specified using one EV1 only instead of two, as described here http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/GLM#Randomise_details-1 - is that because FIRST treats matrices different then FEAT? - groups do not have the same size, does this matter? Thanks a lot in advance and please excuse these “basic" questions! Best regards Falk