Dear SPMers
I have some questions to construct my study design in SPM5.
I have two groups of subject, and each subject will received FDG scan twice
in different menstrual cycle period. Subject's anxiety score was noted
before the tracer injection. I can test the difference between two
conditions (different cycle period) following the example in manual. My
questions are:
1. Since I have patient and normal subject, the "variance" option under the
factor "groups" should keep as "unequal"?
2. To test the relationship between conditions (set as a factor) and anxiety
score, how can I set these scores as a "factor"? I can input these scores as
covariate since there is a "Vector" option to key them in, but where can I
input these score if I wish them is a "factor"?
3. If these anxiety scores serve as covariate in the model, what's the
appropriate centering option?
4. Since my study is deal with FDG image, is there any reference to point
out the impact if the grand mean is normalized to 50? In SPM5, the grand
mean for each scan seems normalized to 50, but previous FDG study seems
normalized to 100.
Very appreciate for any advisement.
Best regards
--
§ù¬F©þ
Cheng-Hao Tu, PhD student
Laboratory of Integrated Brain Research
Department of Medical Research and Education
Taipei Veterans General Hospital
No.201, Sect.2, Shih-Pai Rd.
Taipei
Taiwan
Email: [log in to unmask]
Tel: +886-2-28712121-3476
Fax: +886-2-28757612
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