Dear FSL experts,
I would like to verify if I am on the right track setting up a design for a resting state seed based analysis on a group of 13 subjects with pre and post treatment data. I am trying to set up the design matrix and design contrast to run the higher-level analysis using FEAT. I know I have to use “one group paired t test” but also I want to use “contrast masking” to mask the positive and negative co-activation, that is why I also need to get from the pre and post groups the correspond negative co-activation mean and positive co-activation mean.
I would like to know if the following designs are correct:
….Design matrix:
subject group EV1 EV2 EV3 EV4 … EV13 EV14
1 1 1 1 0 0 0 0
2 1 1 0 1 0 0 0
3 1 1 0 0 1 0 0
.
.
13 1 1 0 0 0 0 1
14 1 -1 1 0 0 0 0
15 1 -1 0 1 0 0 0
.
.
26 1 -1 0 0 0 …. 0 1
……Design Contrast:
TITLE EV1 EV2 EV3 ……… EV12 EV13 EV14
c1: preTx_ positive correlation > post_tx 1 0 0 0 0 0
C2:post_tx positive correlation > pre_tx -1 0 0 0 0 0
C3:pre_tx positive correlation mean 1 1 1 1 1 1
C4:post_tx positive correlation mean -1 1 1 1 1 1
C5: pre_tx negative correlation mean 1 -1 -1 -1 -1 -1
C6: post_tx negative correlation mean -1 -1 -1 -1 -1 -1
C7: preTx_ negative correlation > post_tx -1 0 0 0 0 0
C8: post_tx negative correlation > pre_tx 1 0 0 0 0 0
……Contrast masking:
C1 with C3>0 = “real” preTx_ positive correlation > post_tx
C2 with C4>0 = “real” post_tx positive correlation > pre_tx
C7 with C5>0 = “real” preTx_ negative correlation > post_tx
C8 with C6>0= “real” post_tx negative correlation > pre_tx
Am I doing the right thing?
Any hint on this would be greatly appreciated
Thanks
Lorena
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