What Nia said is correct. You have to create the F contrast mentioned;
then you can choose to adjust for that when you do a VOI. This is
different than specifying the contrast that you want an SPM of.
Jana Basnakova wrote:
> Dear Nia,
>
> thank you for your reply, although I am afraid that my problem is
> something slightly different.
> I actually did specify a contrast for the subject (that's a
> prerequisite of extracting VOI timecourse). However, in the next step
> - when I select a VOI and want to calculate the timecourse of that
> contrast - there is a field where you should specify adjustment and
> select 'effect of interest', according to the SPM guide (there are
> other options as well, for example "no adjustment", which I think is
> the default option).
>
> Jana
>
>
>
> On Tue, Sep 7, 2010 at 5:41 PM, Nia Goulden <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
>
> Dear Jana
>
> The effects of interest contrast needs to be specified manually.
> The effects of interest contrast is an F contrast specified by
> entering the identity matrix (i.e. a matrix of 0s with 1s along
> the diagonal) with the same number of rows and columns as
> conditions in your design matrix.
>
> Hope this helps
> Nia
>
> *From:* Jana Basnakova <[log in to unmask]
> <mailto:[log in to unmask]>>
> *To:* [log in to unmask] <mailto:[log in to unmask]>
> *Sent:* Tue, 7 September, 2010 16:23:29
> *Subject:* [SPM] extracting VOI - 'adjust data' problem
>
> Hi,
>
> I want to extract a VOI in order to do a PPI analysis in SPM5. I
> am following the steps in the manual - I selected the desired
> contrast at the single subject level, chose a voxel, pressed
> "eigenvariate" and then typed in the name of the region (BA44, in
> my case). Next, I am supposed to adjust the data for "effects of
> interest".
> However, this step does not seem to work - when I press "enter"
> after naming my VOI, it skips this field and I automatically get
> to the next field, asking me which for session I want to extract
> the VOI (I had several blocks in my experiment). The field where I
> am supposed to choose the adjustment is automatically filled in
> with "no adjustment".
>
> Is this supposed to be so (why) or am I doing something wrong?
>
> Thank you!
>
> Jana
>
>
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