Mario Beauregard wrote:
> Dear colleague (s),
>
>
> 1) Out of a group of several subjects (n = 17): what would you
> recommend to do with subjects (n = 4) who succeed on a cognitive
> (e.g., memory) task but display very few significantly activated
> voxels, these voxels hardly revealing any temporal correlation with
> the experimental design (that is, they show essentially noise)?
>
> 2) Same question but this time with subjects succeeding on a task
> while showing no significant activation?
>
> 3) Would you keep these subjects for a group analysis? From a
> statistical viewpoint, can we consider that that these subjects are
> outliers?
I don't think you can define outliers because they show UNEXPECTED
results!
> Is it legitimate to remove such subjects a posteriori (to include such
> subjects amounts to markedly influence the outcome of the statistical
> analyses, regardless of whether we use fixed effects model or random
> effects model)?
Why do you perform a statistical analysis at all? Just describe the
results you expect.
>
> Best regards
>
>
> Mario
It's just the statistical idea that outcomes of an experiment can vary.
The question is,
does your experiment succeed 'on average', and not, does it succeed for
every single trial.
Best regards,
Christoff
--
Christoff Gössl
Max-Planck-Institut für Psychiatrie
AG NMR
Kraepelinstr. 10
80804 München
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