Hello again,
I don't see whats wrong with saying 10/12 subjects showed activation at
x,y,z using FWE (p<0.05). Its a precise statement about what you've done
so readers should be able to interpret accordingly. I would'nt use
different criteria for different subjects.
Re the group comparison, you could again take the above approach. But
say 4/12 showed activation in group 1 and 8/12 in group 2, all we have
is this descriptive statement. And it will take you a fair amount of
work to collect together these statements for a number of different
brain regions.
I think it would be better, and it should be easier to use eg. a
two-sample t-test (or ANOVA) at the second level to test for group
differences (where in the brain is the group 1 response sig diff from
group 2). What problem did you run into with the ANOVA (where in the
brain are there any differences between (>2) groups) ?
Best,
Will.
Katelyn Norton wrote:
> Hi all.
>
> I am working with two groups of subjects, each having an n=12. After
> struggling with ANOVA's, I have decided to use whole brain anlyses on each
> subject and simply report "10/12 showed activation here" for example.
>
> First question, is this an acceptable means of reporting data when I will
> essentially be comparing these results on a group vs. group basis?
>
> Second question, is it acceptable to use a different level of correction (p
> value) for each subject or should they all be the same? My hunch is that they
> should all be the same, however the level of activation among subjects is so
> variable that for some I can use FWE and for others I cannot correct all
> (p<0.05).
>
> I would really appreciate any suggestions?
> Thanks!
>
>
--
William D. Penny
Wellcome Trust Centre for Neuroimaging
University College London
12 Queen Square
London WC1N 3BG
Tel: 020 7833 7475
FAX: 020 7813 1420
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URL: http://www.fil.ion.ucl.ac.uk/~wpenny/
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