A statistical test for measuring unimodal clustering: a description of the test and of its application to cases of acute leukemia in metropolitan Atlanta, Georgia.

SUMMARY A combinatorial test for measuring unimodal clustering has been developed. The null distribution of this statistic is derived as well as the power function for a class of alternatives representing exponential contagion. The statistic is asymptotically normal, with prior results indicating the convergence to be fairly rapid. The mean and variance are derived to facilitate the construction of large sample tests. Results of the method applied to cases of acute leukemia among residents of Metropolitan Atlanta, Georgia, over a 14-year period, showed a tendency for cases to cluster in the 0-14 and 50+ age groups.