1. A method for generating a reliability map for analyzing brain images, the method comprising: 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; further dividing the first group into A 1 to A n subgroups; further dividing the second group into B 1 to B n subgroups; determining statistical individual variability between datasets selected from the plurality of three-dimensional image datasets in the A 1 to A n subgroups and the B 1 to B n subgroups; determining statistical individual variability between the plurality of three-dimensional image 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 A 1 to A n subgroups and the B 1 to B n 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 to thereby analyze brain images.