 |
 |
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 > > >