A Statistical Method for Comparing Aggregate Data Across A Priori Groups

This article introduces a new method for statistically comparing pairs of aggregate data series. Aggregate data series refers to a set of values, each of which is averaged or otherwise aggregated across respondents. Themotivating problem is the comparison of aggregate proximity matrices, such as those obtained from pile sort exercises. The standard approach to this problem uses the nonparametric, permutation-based quadratic assignment program (QAP) technique. However, the null distribution that QAP is based on is inappropriate for comparing subsamples of a data set andmay lead tomisleading conclusions. The newmethod can yield different results than QAP, results more in line with researchers’ intuition. Furthermore, the method can be applied to a variety of data types beyond those appropriate forQAP.