Hi Luke
Why not entering 4 columns? 2 columns for your gp and 2 columns for the
personnality + 1 cste
I guess in your previous design group and personnality are confunded; with 4
columns you have the equivaelent of your t test between gp + if you set a 1 and
1 where on the whole it covaries with the ersonality scores and finally you
could contrast personnality score ..
Hope this helps (and is correct :-))
cyril
> I have a design with one group variable (patient vs. controls) and one
> continuous variable (a personality measure). I am using SPM2 and have set up
> the second-level analysis using the Multiple Regression option with two
> regressors, specifying the first column as the patient personality scores
> and entering zeros for the rows pertaining to the control subjects and the
> second column as the control personality scores and entering zeros for the
> rows pertaining to the patients. Thus, I have a design matrix with two
> columns, one column with patient personality information and the other with
> control subject personality information. Then, to test the group (patient >
> control) X personality variable interaction, should I use a [1 -1] t
> contrast or will this give me areas of activation that result from the
> positive correlation with personality variable scores for patients vs. the
> negative correlation with personality scores for controls? Does anyone have
> a better suggestion for how to set up this contrast to effectively test the
> group (categorical variable) X personality measure (continuous variable)
> interaction? I ultimately want to know where brain activation is associated
> with increasing personality variable more in patients than controls. Thanks.
>
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