Hi,
On 17 Feb 2008, at 16:44, bs Jeong wrote:
> Dear FSL experts,
>
> I have a question for performing FSL-VBM (3 groups * 3 time point).
> 1. To make template, do I have to select same number of images from
> 3 time
> point as well as 3 group?
You could just use one time point from each subject from each group or
use all 3, as long as the numbers are matched.
> 2. I have 3 diagnostic group and each subject has 3 images which
> were get
> different time. My hypothesis is that GM intensity will be decreased
> across
> the time ( 1 vs 0 vs -1 for linear decline)and the slop of decrease
> will be
> different among 3 groups (1 vs 1 vs -2: former 2 groups will not be
> different but GM intensity of 3rd group will be more decreased.) and
> there
> will be group by time interaction. But to make design matrix (for main
> effects and group by time interaction) is not easy for me.
> If each group has 3 subject, I think design matrix like below. But
> I'm not
> sure it is correct and don't know the matrix for group by time
> interaction.
I don't think your example is correct - I think you want the tripled-t-
test example in the FEAT manual (see higher-level examples).
> 3. And do I have to make group.dat file which consist of nine 1s,
> nine 2s,
> nine 3s?
Yes, see the randomise manual for information about repeated measures.
Steve.
>
>
> I'd be very happy if I can hear any comment.
>
> thanks,
>
> bsjeong
>
> sj1 sj2 sj3 t1 t2 t3 time
> group
> gr1_sj1_t1 1 0 0 1 0 0 1
> 1
> gr1_sj1_t2 1 0 0 0 1 0 0
> 1
> gr1_sj1_t3 1 0 0 0 0 1 -1
> 1
> gr1_sj2_t1 0 1 0 1 0 0 1
> 1
> gr1_sj2_t2 0 1 0 0 1 0 0
> 1
> gr1_sj2_t3 0 1 0 0 0 1 -1
> 1
> gr1_sj3_t1 0 0 1 1 0 0 1
> 1
> gr1_sj3_t2 0 0 1 0 1 0 0
> 1
> gr1_sj3_t3 0 0 1 0 0 1 -1
> 1
> gr2_sj1_t1 1 0 0 1 0 0 1
> -2
> gr2_sj1_t2 1 0 0 0 1 0 0
> -2
> gr2_sj1_t3 1 0 0 0 0 1 -1
> -2
> gr2_sj2_t1 0 1 0 1 0 0 1
> -2
> gr2_sj2_t2 0 1 0 0 1 0 0
> -2
> gr2_sj2_t3 0 1 0 0 0 1 -1
> -2
> gr2_sj3_t1 0 0 1 1 0 0 1
> -2
> gr2_sj3_t2 0 0 1 0 1 0 0
> -2
> gr2_sj3_t3 0 0 1 0 0 1 -1
> -2
> gr3_sj1_t1 1 0 0 1 0 0 1
> 1
> gr3_sj1_t2 1 0 0 0 1 0 0
> 1
> gr3_sj1_t3 1 0 0 0 0 1 -1
> 1
> gr3_sj2_t1 0 1 0 1 0 0 1
> 1
> gr3_sj2_t2 0 1 0 0 1 0 0
> 1
> gr3_sj2_t3 0 1 0 0 0 1 -1
> 1
> gr3_sj3_t1 0 0 1 1 0 0 1
> 1
> gr3_sj3_t2 0 0 1 0 1 0 0
> 1
> gr3_sj3_t3 0 0 1 0 0 1 -1
> 1
>
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR 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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