Dear Boris,
the following paper describes the fixed-effects analysis (Group Bayes Factors)
and the new random-effects method (and its variables) now implemented
in SPM8:
http://www.ncbi.nlm.nih.gov/pubmed/19306932/
This one might also be useful:
http://www.ncbi.nlm.nih.gov/pubmed/15219588/
The variables stored in BMS.DCM correspond to what is plotted on the
SPM graphics window, but it also includes some additional information
(please check the
Help text in the batch editor window for further information):
BMS.DCM.ffx (Fixed-effects analysis):
'.F' is the Free Energy (or log-model evidence) for each model/subject
'.P' is the Posterior Probability for each model (as plotted)
'.SF' contains the sum of the log-evidence (F) for each model
'.data' contains the path to the DCM files (for each subject/session
and model) that were used in the analysis.
BMS.DCM.rfx (Random-effects analysis):
'.F' is the Free Energy (or log-model evidence) for each model/subject
'.SF' contains the sum of the log-evidence (F) for each model
'.data' contains the path to the DCM files (for each subject/session
and model) that were used in the analysis.
'.exp_r' is the expected posterior probability for each model
'.xp' is the exceedance probability for each model
'.alpha' are the estimated parameters of the Dirichlet distribution
for each model
I hope this helps.
Best Regards,
Maria
On Mon, Apr 20, 2009 at 8:59 AM, boris suchan
<[log in to unmask]> wrote:
> Fan Cao schrieb:
>
> Thanks,
> but this is true for SPM5.
> in SPM8 you get something like
> F
> P
> SF
>
> and the plots show log evidnece and posterior model probability....
> so any suggestions????
>
> Many thanks
>
> boris
>
> AIC, BIC >2.72
>
> On Fri, Apr 17, 2009 at 8:07 AM, boris suchan
> <[log in to unmask]> wrote:
>>
>> Hi all,
>> I am not sure how to handle the DCM model comparison resulst from SPM8?
>> I get probabilities for each model.after the comparisons.
>> What is the threshold to favour one model against the other one?
>> Many thanks
>> boris
>>
>> --
>> Priv.- Doz. Dr. Boris Suchan
>> Institute of Cognitive Neuroscience
>> Department of Neuropsychology
>> GAFO 05/613
>> Universitätsstrasse 150
>> 44780 Bochum
>> phone: + 49 234 3227575
>> mailto:[log in to unmask]
>>
>
>
>
> --
> Priv.- Doz. Dr. Boris Suchan
> Institute of Cognitive Neuroscience
> Department of Neuropsychology
> GAFO 05/613
> Universitätsstrasse 150
> 44780 Bochum
> phone: + 49 234 3227575
> mailto:[log in to unmask]
|