Ladau, J.

A long-standing question in ecology is whether interspecific competition affects co-occurrence patterns of species. Null model tests of presence-absence data (NMTPAs) constitute an important approach to address the question, but different tests often give conflicting results when applied to the same data. Neyman-Pearson hypothesis testing theory provides a rigorous and well accepted framework for assessing the validity and optimality of statistical tests. Here, I treat NMTPAs within this framework, and measure the robustness and bias of 72 representative tests. My results indicate that, when restrictive assumptions are met, existing NMTPAs are adequate, but for general testing situations, the use of all existing NMTPAs is unjustified-the tests are nonrobust or biased. For many current applications of NMTPAs, restrictive assumptions appear unmet, so these results illustrate an area in which existing NMTPAs can be improved. In addition to highlighting useful improvements to existing NMTPAs, the results here provide a rigorous framework for developing improved methods.