Yes, that looks right.
Cheers.
On Wed, 23 Nov 2005, Brad Goodyear wrote:
> Thanks for your response Steve.
>
> Does this mean that within the contrast masking tab
> you would Mask real contrast 3 with C1 and C2 and mask using Z>0
> instead of Z stats pass threshold?
>
> -BRad
>
> On Sep 7, 2005, at 12:25 AM, Stephen Smith wrote:
>
> > Hi Brad, this looks fine. The ony possible gotcha is in the
> > interpretation
> > of the final contrast - note that it is actually asking A-B-C+D -
> > so you
> > may want to use the "contrast masking" function in the poststats
> > tab to
> > make sure perhaps that both A-B and C-D are positive in the areas
> > shown by
> > the final contrast.
> >
> > Cheers, Steve.
> >
> >
> > On Tue, 6 Sep 2005, Brad Goodyear wrote:
> >
> >
> >> I have a somewhat simple analysis to perform, but I'm not quite sure
> >> how to set it up.
> >> Let's say I have 3 subjects (S1, S2, S3), each scanned under
> >> conditions
> >> A,B,C, and D.
> >> I am interested in comparing A vs B and C vs D. But I am also
> >> interested in the comparison (A-B)vs(C-D).
> >> Would the following capture this?
> >>
> >> Input EV1(S1 mean) EV2(S2 mean) Ev3(S3 mean)
> >> EV4(AvsB) EV5(CvsD)
> >> S1:A 1 0
> >> 0 1 0
> >> S2:A 0 1
> >> 0 1 0
> >> S3:A 0 0
> >> 1 1 0
> >> S1:B 1 0
> >> 0 -1 0
> >> S2:B 0 1
> >> 0 -1 0
> >> S3:B 0 0
> >> 1 -1 0
> >> S1:C 1 0
> >> 0 0 1
> >> S2:C 0 1
> >> 0 0 1
> >> S3:C 0 0
> >> 1 0 1
> >> S1:D 1 0
> >> 0 0 -1
> >> S2:D 0 1
> >> 0 0 -1
> >> S3:D 0 0
> >> 1 0 -1
> >>
> >> with contrasts:
> >>
> >> C1 (A vs B): 0 0 0 1 0
> >> C2 (C vs D): 0 0 0 0 1
> >> C3 (a-b vs c-d): 0 0 0 1 -1
> >>
> >> or do I need an EV to code the a-b vs c-d directly?
> >>
> >> -BRad
> >>
> >>
> >
> > --
> > Stephen M. Smith DPhil
> > Associate Director, FMRIB and Analysis Research Coordinator
> >
> > Oxford University Centre for Functional MRI of the Brain
> > John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
> > +44 (0) 1865 222726 (fax 222717)
> >
> > [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
> >
>
--
Stephen M. Smith DPhil
Associate Director, FMRIB and Analysis Research Coordinator
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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