Dear Freja,
Freja Gheysen wrote:
> Dear all,
>
> When using Bayesian 2nd level analyses with SPM5 and computing PPM’s,
> I sometimes get the message "no suprathreshold clusters" even when
> lowering the prior to 0
I think you must mean 'lowering the effect size to zero'.
and lowering the posterior probability
> threshold to 0 and even though this analysis works perfectly in other
> contrasts for the same ROI.
Yes - this is odd.
Have a look at the estimated beta image for the contrast. If your
contrast has a single 1 in eg the third position then its cbeta03.img
that you need to look at.
If there are positive values in this image they should show up in the
PPM.
If you still have a problem send me your SPM.mat file & con images (if
its only a few).
Best, Will.
>
> Does anyone ever encountered a similar problem or has any idea what
> could go wrong here? I would greatly appreciate any help on this
> issue!
>
> kind regards, Freja Gheysen
>
>
--
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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