A method including generating a first overlap matrix from a first attribute having first measurements of data items, and generating a second overlap matrix from a second attribute having second measurements of the data items. Samples of weights are generated, each of the samples of weights including a corresponding first weight for the first overlap matrix and a corresponding second weight for the second overlap matrix. For each of the samples of weights, the first overlap matrix is combined with the corresponding first weight and the second overlap matrix is combined with the corresponding second weight. Similarity matrices are generated by combining, for each of the samples of weights, a weighted first overlap matrix with a weighted second overlap matrix. A cluster analysis is performed on the similarity matrices to generate groupings the similarity matrices. The groupings represent groups of the data items. A selected grouping is chosen.