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Petra > -----Original Message----- > From: SPM (Statistical Parametric Mapping) > [mailto:[log in to unmask]] On Behalf Of Petra Tomse > Sent: Wednesday, February 20, 2008 7:09 AM > To: [log in to unmask] > Subject: [SPM] cluster signal > > Hello List, > > I am doing a SPECT analysis (paired t-test) with spm2 and I > would like to get the value of the activity in the clusters, > that analysis showed were significant. In my case I would > expect the activity in the cluster to be higher post-therapy > (2nd images of Patients), but it seems not to be, or I don't > understand it... > > I understand that Eigenvariate produced by the VOI is > connected to activity value. The Eigenvariates of my > significant clusters have values of about 60 or 70. This should be around the same values as your actual data. > > My question is: What is the unit of the Eigenvariate? I believe they are parameter estimate units (what is called "response" in the plots). Basically the eigenvariate is just a method for summarizing the data from all the voxels in your VOI. A more familiar method would be to take a mean at each data point, across voxels. The eigenvariate is just another way of summarizing this data that accounts for most of the variance in the data vector. > In what order are the values of Eigenvariate given? (is it: from 1st > image of Patient1; 2nd image of Patient1; 1st image of > Patient2;... ? ) In whatever order you have entered the scans in your model. Darren > > Thank you in advance, > Petra > -- > Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! > Ideal für Modem und ISDN: http://www.gmx.net/de/go/smartsurfer >