 |
 |
Dear Dima, the new BMS interface has been added recently to SPM, so you might need to update your SPM in order to access it. Best, Maria On Tue, Mar 31, 2009 at 4:04 PM, <[log in to unmask]> wrote: > 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 >> > >> >