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Hi David, That’s fine – not every subject needs individual level activation (although this could indicate different subjects are using different cognitive processes?). A note of caution in case you’re using the GUI to extract ROIs… When you click the ‘eigenvariate’ button, the crosshairs will jump to the nearest activation. To prevent this you’d have to set the significance threshold to a very liberal value. Best, Peter. From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of David Hofmann Sent: 29 July 2014 13:41 To: [log in to unmask] Subject: [SPM] DCM: Group comparison & defining ROIs Hi @all, when defining ROIs for a DCM group analysis, is it necessary that in every subject those ROIs need to be significantly activated (e.g. with F-test over all effects of interest at p = 0.001 uncorrected)? With 2nd level analysis I can define some ROIs with significant activation, but those are not active in every single person. greetings David