Dear SPM list,
I am trying to enter contrasts for my paired t analysis but cannot
seem to enter the correct contrasts. For my experiment, I have 9
subjects who were scanned on both a GE and Siemens scanner. So, the
conditions are GE (1) and Siemens (2). We are also trying to
determine if using scanner as a covariate will properly alleviate any
differences we may see. I entered my paired scans as Pair 1: 1-GE,2-
Siemens; Pair 2: 1-GE, 2-Siemens, etc. The contrast I want to run is
condition 1 - condition 2 (GE-SN).
So far I have tried the following without success:
t-test
repmat(0,1,9) 0 1 -1
repmat (0,1,10) 1 -1
0 0 0 0 0 0 0 0 0 1 -1
F test
reduce columns 1:10
Please advise me on how to enter the contrast for an analysis of GE
scans - Siemens scans (Condition 1 - Condition 2).
I have a attached a jpeg of the design matrix for clarification.
Thank you very much, in advance, for your help,
Christa
Christa Watson
Center for Interdisciplinary Brain Sciences Research
Stanford University
Dept. of Psychiatry and Behavioral Sciences
401 Quarry Road, MC 5795
Stanford, CA 94305-5795
phone: (650) 736-0732
email: [log in to unmask]
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