Hi Maria,
First of all thanks for the answer.
Unfortunately, I can not access the Bayesian Model Selection through the Batch as you suggest. It is not there. And does not appear when I finish the DCM analysis. I can only press the BMC button. Do you maybe know which script does the BMS?
Best,
Danai
----- Original Message -----
From: Maria Joao <[log in to unmask]>
Date: Tuesday, March 31, 2009 4:46 pm
Subject: Re: [SPM] Bayesian model selection in EEG-DCM
> Dear Dima,
>
> SPM8b has a new interface for group BMS (access through Batch >
> SPM >
> Stats > Bayesian Model Selection > BMS: DCM).
> This new batch editor window will also appear when you click BMS at
> the end of your DCM analysis.
>
> This interface allows one to select the data (log-model evidence
> values) for each subject/session/model and choose which
> inference method to use (Fixed-effects or Random-effects, as described
> in Stephan et. al. 2009).
>
> If you choose Random effects then SPM will compute, among other
> things, the exceedance probabilities for each model. This information
> will
> be displayed in the graphics window and stored in the BMS.mat file.
> This file contains:
>
> 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 this 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 this 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 Joao
>
>
>
>
> On Tue, Mar 31, 2009 at 2:10 PM, <Danai> <Dima>
> <[log in to unmask]> wrote:
> > Dear all,
> >
> > I just read the article 'Bayesian model selection for group studies'
> >
> >
> http://www.ncbi.nlm.nih.gov/pubmed/19306932?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum>
> > and I wanted to ask how can I compute the exceedance probability
> in ERP data. Is there already a script implemented in the SPM8b? I
> have already compared 2 models and I have the conditional model
> probability.> I looked up the SPM_BMS, but I do not know how to
> run it for my EEG data. Or is there another solution?
> >
> > Thanks for any help
> >
> > Best,
> >
> > Danai Dima
> >
>
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