Ramesh,
Your design matrix tells me you have selected more than one group. All ADHD images should in one group and all controls should be in another.
What extent threshold did you use?
Also test your significance for 95% confidence (0.05).
Abhinay
Wayne, PA
Ph: 817-995-3962
On Sep 8, 2011, at 12:44 PM, "M.G. Ramesh Babu [MU-KMCIC]" <[log in to unmask]> wrote:
> Dear Members
> I have downloaded ADHD data set (n=48) from Neuro Image site, consists of developing control n=23 and ADHD (including subgroups) n=25. After preprocessing, I have done 2 sample T test as prescribed in VBM manual (Chritean G). I defined t contrat 1 -1 to get CTRLl > ADHD. I got blank images. Then i defined t-contrst -1 1 to get ADHD > CTRL. I Found changes in the gray matter regions (please see the attached files). Since there are changes in the gray mater region in for ADHD>CTRL, it shows gray matter volume in certain region in ADHD is greater than control. AM I correct? And I got these changes when significant level is kept <0.001. For any other significant level I didn't find out any changes (got only blank image in SPM graph) for both contrast. I will be very thankful if any one could give their suggestion/comment?
>
> With Thanks
> M.G.Ramesh Babu, BPT., MSc
> Lecturer in Physiology & Neuroscience,
> KMC-IC,
> Manipal-576104
> Karnataka
> India
> +91-820-2933035
> +919611362075
> <ADHD-CTRL.png>
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