A method for analyzing brain images includes receiving a plurality of three-dimensional image datasets comprising a plurality of voxels for a corresponding plurality of subjects； dividing the plurality of three-dimensional image datasets into at least a first and a second group； dividing the first group into A1 to An subgroups； dividing the second group into B1 to Bn subgroups； determining statistical individual variability between datasets selected from the A1 to An subgroups and the B1 to Bn subgroups； determining statistical individual variability between datasets in the first and second groups responsive to the statistical individual variability between datasets selected from the plurality of three-dimensional image datasets in the A1 to An subgroups and the B1 to Bn subgroups； and for each of the first and second groups, generating a reliability map comprising a map of probabilities that a voxel in an image dataset of the respective first and second groups satisfies a predetermined statistical threshold.
