Hi Deqiang,
> Thank you for your kind reply. My concern is that if I want to do an
> "optimized VBM" by creating my own template, will the excessive number
> of normal control bias the normalization process and the result by
> having high weighting in my own template?
Actually, if you want to do VBM on this very small sample of yours you
should be much more worried about this than about including not enough
controls. True, the more uneven your samples become the more biased your
template will be BUT with VBM, starting with 6 subjects would not really
cross my mind in the first place. And with 13 or so, creating your own
template is likely not a good idea anway, and probably not necessary in
spm5. What Cyril said is even more important here: MORE IS BETTER.
Best,
Marko
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Marko Wilke (Dr.med./M.D.)
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Universitäts-Kinderklinik University Children's Hospital
Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology)
Hoppe-Seyler-Str. 1, D - 72076 Tübingen
Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473
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