Hi - a [1 0] contrast will give you the mean task effect and [0 1]
will tell you how age modulates it.
Ah - sorry - I probably also should have added - you should probably
demean all of the ages before using them in this way in the model.
Cheers.
On 14 Sep 2009, at 12:51, Tessa Dekker wrote:
> Hi Steve,
>
> thanks a lot for your help. As for the contrast, do I get a cope of
> the
> AGEXTASK interaction by giving a 1 weighting to both the task
> comparison and
> the age EV (e.g.,C_interaction: 1 1 0 0 0 0 0 0)? Or does a contrast
> with
> only a 1 for task now give the interaction (1 0 0 0 0 0 0 0) ?
>
> thanks,
>
> Tessa
>
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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)
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