Hello!
sorry, for reposting the same question but I really need to know what I am doing is alright.Thank you!
I have an experiment with two groups (patients and controlls). Unfortunately patients have sig. higher scores on scales for depression and trait-anxiety. I want to control for this two variables in my group analyses. I have demeaned the depression and anxiety scores and included them in my GLM as EV3 EV4. Now; I have two questions about the GLM.
1) Feat finds it rank deficient, when I name two groups (Group (111.....11112222.....22222) the very first column).I have always done it this way for a normal higher level analyses without covariates. I really don't get, why it is okay to name two seperate groups, when I make the analyses without additional covariates and why it is not, when I have the additional covariates. Is it allright, how I did it?: (Group 1111.....1111...11111)
Group EV1 EV2 EV3 EV4
Patients Cont. Dep. Anxiety
Input1 1 1 0 10.5 12.3
Input2 1 1 0 3.4 7.5
....
Input30 1 0 1 -1.5 2.1
..
Input57 1 0 1 2.3 -3.4
Contrasts
title EV1 EV2 EV3 EV4
C1 Patients mean 1 0 0 0
C2 Cont. mean 0 1 0 0
C3 Pat.> Cont 1 -1 0 0
C4 Cont.> Pat. -1 1 0 0
C5 whole sample 1 1 0 0
2) My second question is how to see the activation in relation to another questionaire score but still to controll for depression and anxiety score. How shall I make the contrast matrix for this purpose? In this case the demeaned scores from this questionaiere will be EV5.
title EV1 EV2 EV3 EV4 EV5
Patients Cont. Dep. Anx. Questionaire X
C1 Patients mean 1 0 0 0 0
C2 Cont. mean 0 1 0 0 0
C3 Pat.> Cont 1 -1 0 0 0
C4 Cont.> Pat. -1 1 0 0 0
C5 whole sample 1 1 0 0 0
C6 new questionaire 0 0 0 0 1
Does it make sense to set all EVs to zero and just that "questionaire" EV to 1, in order to see the voxels, which have a signifikant correlation with this score(questionaire X) but also control for depression and anxiety.
I hope,I managed to make the problems clear. I will really appreciate an answer!
Best Regards
Elif
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