Hi list,I'm performing qdec. This my file.dat1 diagnosis discrete 2 1 Pathology 2 Controls2 Thickness_lh continuous 03 Thickness_rh continuous 04 NPStest continuous 0 Continuous Factors: Mean: StdDev: ------------------- ----- ------- Thickness_lh 2.643 0.116 Thickness_rh 2.630 0.099 NPStest 0.774 1.203Number of subjects: 31Number of factors: 4 (1 discrete, 3 continuous)Number of classes: 2Number of regressors: 8NPStest is scored from 0 to 8 and for controls it is all 0.Previously I have performed qdec without problem but I'm noting that when I use covariates that contains all 0 in a group, qdec give me an error. What's happen?Thanks,

Stefano