Hi All,

We’re struggling with some two-sample results.  Our metric here are beta-weights, and both groups have negative average values for a certain voxel/region.  Now, when you run the patients as group 1 and healthy controls as group 2, set up a [1,-1] contrast (patient > HC), will this voxel/region show up if the patients have a more negative value?  If the average in our VOI/ROI is, say, -3.5 for patients and -1.5 for HC, which contrast will have this area pop out?

Related: is the default for two-sample ttests in SPM5 two-tailed or one-?

Thanks!

James