Hi, I have calculated the group differences for volume using both FreeSurfer GLM and SPSS GLM. I have used gender and group as fixed factor and intercranial volume and age at MRI scan as covariate.
GroupDescriptorFile 1 Title group_difference_between_group1_and_group2_gender_age DeMeanFlag 1 Class Group2Male Class Group2Female Class Group1Male Class Group1Female Variables ICU Age
I used this as fsgd heading, and I used this contrast vector 0.5 0.5 -0.5 -0.5 0 0 0 0 0 0 0 0 to be able to control for gender difference and difference due to age and ICU. I get difference results between SPSS and Freesurfer. I think this is strange since I used the same data both in FreeSurfer GLM and SPSS glm. Is there anything I have done wrong? I have used both univariate and multivariate in SPSS glm.
Best regards Knut J