MPowering ecologists: community assembly tools for community assembly rules

Null model tests of presence–absence data (‘NMTPAs’) provide important tools for inferring eff ects of competition, facilitation, habitat fi ltering, and other ecological processes from observational data. Many NMTPAs have been developed, but they often yield confl icting conclusions when applied to the same data. Type I and II error rates, size, power, robustness and bias provide important criteria for assessing which tests are valid, but these criteria need to be evaluated contingent on the sample size, null hypothesis of interest, and assumptions that are appropriate for the data set that is being analyzed. In this paper, we confi rm that this is the case using the software MPower, evaluating the validity of NMTPAs contingent on the null hypothesis being tested, assumptions that can be made, and sample size. Evaluating the validity of NMTPAs contingent on these factors is important towards ensuring that reliable inferences are drawn from observational data about the processes controlling community assembly.