Hi venkateswaran,
sorry I missed your previous email. You contrast matrix looks good to me if:
1) your evs are put in this order: N-D-C-B-E (not N-B-C-D-E) and it follows the concatenation of the GM_mod images
2) you only expect:
controls to have more GM than patients (i.e. N>D,C,B,E)
D>C,B,E
C>B,E
B>E
If you actually also think that there might be something like E>D, you should also look at the opposite contrast.
Finally, why are you surprised that there is only difference between N and D? Is D the less affected of your patient group?
If it's the most affected, then it makes sense, but then you should also reverse the contrasts when comparing one by one all the patient groups (cf 2nd point above)...
Cheers,
Gwenaelle
--- En date de : Mer 7.10.09, Rajagopalan, Venkateswaran <[log in to unmask]> a écrit :
> De: Rajagopalan, Venkateswaran <[log in to unmask]>
> Objet: [FSL] Contrast matrix for one way ANOVA-VBM
> À: [log in to unmask]
> Date: Mercredi 7 Octobre 2009, 23h48
>
>
>
>
> Dear fsl users,
>
> I performed VBM on T1-w struc data on 4 patient groups
> and a control group. I compared them in the following
> way using ANOVA for instance control group is N and patient
> groups are B,C,D,E. so my contrats are N-B, N-C,N-D,N-E and
> between patient groups D-C,D-B,D-E, C-B,C-E and C-E.
> Except in N-D case there is no significant difference
> between other groups which is kind of suspecious to me.
> I am wondering whether i have made any mistake in my
> contrast matrix. I am attaching my contrast matrix could
> anyone please tell me whether it is correct or not, i am new
> to VBM.
>
> Thanks in advance,
>
> Regards
> venkateswaran
> ===================================
> P
> Please
> consider the environment before printing this
> e-mail
>
> Cleveland Clinic is ranked one of the top hospitals
> in America by U.S. News & World Report (2008).
> Visit us online at http://www.clevelandclinic.org for
> a complete listing of our services, staff and
> locations.
>
>
> Confidentiality Note: This message is intended for use
> only by the individual or entity to which it is addressed
> and may contain information that is privileged,
> confidential, and exempt from disclosure under applicable
> law. If the reader of this message is not the intended
> recipient or the employee or agent responsible for
> delivering the message to the intended recipient, you are
> hereby notified that any dissemination, distribution or
> copying of this communication is strictly prohibited. If
> you have received this communication in error, please
> contact the sender immediately and destroy the material in
> its entirety, whether electronic or hard copy. Thank you.
>
|