Hello fellow SPMers,
I performed a one-sample t-test to identify differences in activation levels
between a patient and a group of control scans. I selected my patient scan
first and then the 8 control scans. I used covariates as follows [0 1 1 1 1
1 1 1 1]. I created a contrast of [1 -1] to look at increases in the patient
versus the controls and I have a very interesting picture, which I have
attached. I said "no" to all the questions and used the default threshold
p=0.001. Am I doing something wrong? I also tried using covariates such as
[1 0 0 0 0 0 0 0 0], which gives a different result. I guess I don't really
understand what covariates are, is there an explanation somewhere? Or maybe
it is my contrasts, should I use [1 0] to look for higher activations in the
patient brain compared to normals or [1 -1]?
Thanks and Happy Holidays!
Anita
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