Group functioning and performance in different contexts is related to the extent to which group members are complementary or supplementary in terms of psychological attributes. This paper describes a procedure for quantifying the degree of dissimilarity at group level. Unlike most existing techniques the one described here is normalized and is both location and scale invariant, thereby making it suitable for comparing dissimilarity on interval and ratio scales with different ranges and in groups of different sizes. Dissimilarity is measured in relative terms regardless of the exact place on the scale at which individuals are located. When a combination of several scales is not theoretically justified, the dissimilarity for each scale can be quantified. Additionally, dyadic and individual contributions to either the global or scale index can be obtained. The descriptive measures are complemented by statistical significance values in order to compare the results obtained with several discrete distributions of reference, both symmetrical and skewed, which can be specified using the expressions developed. The information that can be provided by the indices and the "p" values -- both obtainable through an R package -- is illustrated using data from an empirical study.