Hi,
I am analyzing a huge bunch of data (>300 T1 MRI) coming from three different scanners in a VBM analysis. I am not interested in studying the effect of the scanner by itself and I would like to remove this effect. I am not sure what to do. If I state this as an EV, I will have to set values to e.g. 1, 2 and 3 (before demeaning). It would mean that scanners 1 and 2 are more resemblant than 1 and 3, which is not true.
Or should I model them as 3 "groups" in Glm such as :
Group EV1 EV2 EV3
0
0
0
0
1
1
1
1
2
2
2
????
Thanks
Josselin Houenou
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