Dear Karl,
I have been trying to figure out how to enter data and interpret the
output in SPM5. To do this, I compared the same analysis done in SPM5b. I
appreciate your help, as I cannot find any answer to my questions on the
mailbase. I also took a look at the manual, but still I must make sure I
am doing the analysis correctly.
Design (SPECT images):
patients (no treatment group) visit 1 ( [1 1])====> patients (no treatment
group) visit 2 ([1 2])
patients (treatment group) visit 1 ( [2 1]) ==treatment===> patients
(treatment group) visit 2 ([2 2])
Covariates for all groups entered
Nuisance for all groups entered
**********************************
Data entry:
Full factorial
Two factors each with 2 levels (because 2 x 2 factorial)
four cells: [1 1] [1 2] [2 1] [2 2]
Covariate: centered around overall mean and interaction with Factor 1
Nuisance: cetered as implied my ANCOVA (it seems to me this makes it
nuisance instead of covariate of interest). No interactions.
**************************
Contrasts (this is critical for me to makes sure I undestand):
0 0 0 0 -1 1 0
where:
0 0 0 0 are for the four groups
-1 1 is for interactions between covariate and factor 1. This looks at
the changes in regional perfusion due to [2 1]==>[2 2] more than [1 1]===>
[1 2]. I just figured this out by comparing to SPM5 although based on one
of your previous e-mails the contrasts in SPM5b for covariates are not
entered this way. However, I need to be sure and I would greatly
appreciate your comments as always. I am sure your comments will help the
other colleagues too.
Attached please find the screen shots of the output and the matrix.
Have great holidays and happy new year.
Cheers,
Shary
Shahryar Rafi-Tari, M.Sc.
Database Consultant / Imaging Analyst
ADNI Imaging Project Coordinator at Sunnybrook
2075 Bayview Avenue
Sunnybrook & Women's College Health Sciences Centre
Linda C Campbell Cognitive Neurology Research Unit
Room B630
Toronto, Ontario, Canada M4N 3M5
E-mail: [log in to unmask]
Tel: 416-480-6100 ext. 3281
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