Dear Expert So here is my PALM design (generated by GLM): EV1: female patient EV2: female control EV3: male patient EV4: male control EV5: age of the female patient EV6: age of the female control EV7: age of the male patient EV8: age of the male control *Group Variable is set up differently for each group. Group EV1 EV2 EV3 EV4 EV5 EV6 EV7 EV8 1 1 0 0 0 20 0 0 0 2 0 1 0 0 0 30 0 0 3 0 0 1 0 0 0 40 0 4 0 0 0 1 0 0 0 50 According to "Two Groups with continuous covariate interaction" in this fsl GLM webpage : http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/GLM#Two-Group_Difference_Adjusted_for_Covariate I can only use this model to test the group x age interaction….and nothing else? I did not find any significant group x age interaction, but I got interesting sex effect and group x sex interaction using this model…..can I still use these results??? Thanks so much!!!