In its broad aspect, the invention provides a method for analyzing relationships among patterns within a data set having a set of samples and associated attribute values defining each attribute of each said sample. The method comprises receiving at an input at least two patterns; defining a data cluster within the data set for each of said at least two patterns, each defined data cluster having samples with attribute values associated with a corresponding pattern of said at least two patterns; grouping at least some of the samples of each defined data cluster with one another to generate a resultant data cluster; and calculating a variation between the attribute values of a first set of samples and the attribute values of a second set of samples within said resultant data cluster, the attribute values of the first set of samples and the second set of samples corresponding to the same attribute.