A weighted average likelihood ratio test for spatial clustering of disease

We consider methods proposed for detecting localized spatial clustering. We propose a new test statistic, the weighted average likelihood ratio test, as an alternative to the spatial scan (maximum likelihood ratio) test stati stic. Two different types of weights are considered. We propose an unbiased cluster selection criterion and evaluate the bias of the tests through sim ulation. We also examine the power of the tests through simulations and app ly the methods to the well-known New York leukaemia data. Copyright (C) 200 1 John Wiley & Sons, Ltd.