I would make the model simpler. I would compute the difference images for each subject, then do a two-sample t-test with group (where group is the order).
You could also add order as a group factor in a flexible factorial model.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Postdoctoral Research Fellow, GRECC, Bedford VA
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
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Dear SPMers
I have ran a one-way ANOVA within subjects, with 20 subjects
Entering 2 scans each subject Scan 1 drug scan 2 placebo
I now want to add a covariate of ORDER
Is this just a string 40 numbers with 1 for scan was week 1 and 2 for scan was week 2?
And can I do the same for gender?
Thanks
Ciara
Dr Ciara McCabe
Neuroscience Building
Dept of Psychiatry
Warneford Hospital
Oxford University
Oxford
OX3 7JX
Tel: 01865 223778
Mob: 07966035631
http://www.psychiatry.ox.ac.uk/research/researchunits/perl/perlmembers/ciaramccabe/