Dear Dr Friston, hello all, we would like to seek your advice on a question regarding a conjunction analysis performed on VBM data. In brief, we are not sure whether it is the global or the conjunction null hypothesis to test to answer a specific question. Background: repeated measures of psychopathological ratings were decomposed into orthogonal polynomials that were then used for correlation analysis with GM maps to inform about predictions of the clinical course from morphology. We have calculated separate T-maps for voxels correlating with the linear trend and voxels correlating with the cubic trend. From another analysis with clinical data we know that when combined, the linear and cubic trend excellently reflect "early response". The idea was to identify regions that support this "early response" - which we thought would mean that the test should show voxels that correlate into the defined directions to some degree (however, not necessarily as much as in the separate tests) and that 'work together' to explain this very specific clinical pattern. We have had a look at your paper on conjunction analysis, 2005, and understood that the 'rejection region' shown in figure 2 implies that if the global null hypothesis is rejected, both T-values still have a certain height. Expectedly, testing the global null gives a stronger contrast than testing the conjunction null hypothesis. The question now arised, if a voxel survived the global null testing, how much of the second effect is 'minimally' contained? Intuitively it seems that testing the conjunction hypothesis is too conservative, we are very grateful on any opinion on this. Thank you very much in advance, Philipp Saemann