Hi
yes, that's absolutely right - in fact, each of the examples can be
re-written so that you move some bit of complexity from the design
into the contrasts or vice versa. In the case of the triple t-test
we've opted for the other design so that EV1 and EV2 are mean 0 - the
alternative model you're using below only seems simpler once one has
seen the ANOVA example, i.e. got to grips with the fact that the 1 0
0 0 0 0 0 contrast is not A but A-C... ;)
cheerio
c
On 31 Jul 2007, at 22:37, Sophie Anisa wrote:
> Just to conclude this discussion, now that I understand
> this example more clearly, is it the case that the
> triple t-test example shown on the FEAT web page
> could be made simpler using the different model:
>
> EV1 EV2 EV3 EV4 EV5 EV6 EV7
> 1 0 1 0 0 0 0
> 1 0 0 1 0 0 0
> 1 0 0 0 1 0 0
> 1 0 0 0 0 1 0
> 1 0 0 0 0 0 1
> 0 1 1 0 0 0 0
> 0 1 0 1 0 0 0
> 0 1 0 0 1 0 0
> 0 1 0 0 0 1 0
> 0 1 0 0 0 0 1
> 0 0 1 0 0 0 0
> 0 0 0 1 0 0 0
> 0 0 0 0 1 0 0
> 0 0 0 0 0 1 0
> 0 0 0 0 0 0 1
>
> where the contrasts would now be:
>
> EV1 EV2 EV3 EV4 EV5 EV6 EV7
> A-B 1 -1 0 0 0 0 0
> A-C 1 0 0 0 0 0 0
> B-C 0 1 0 0 0 0 0
>
>
> Or is this not the same?
>
>
> kind regards
>
> Sophie
____
Christian F. Beckmann
University Research Lecturer
Oxford University Centre for Functional MRI of the Brain (FMRIB)
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
[log in to unmask] http://www.fmrib.ox.ac.uk/~beckmann
tel: +44 1865 222551 fax: +44 1865 222717
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