Testing Random Effects for Binomial Data
Lucas Kania, Larry Wasserman, Sivaraman Balakrishnan
TL;DR
This work develops a locality-aware, minimax framework for goodness-of-fit and homogeneity testing of random effects in binomial data, using the 1-Wasserstein distance to compare mixing distributions. The authors introduce two complementary tests—the plug-in $W_1$ test and a debiased Pearson's $\chi^2$ test based on Kravchuk polynomials—and show they are minimax-optimal up to constants, with explicit separation rates that depend on $n$ and $t$. They extend the analysis to both reference-driven and reference-free homogeneity problems, deriving reductions to fixed-effects testing and constructing debiased Cochran's $\chi^2$ variants for unknown-null settings. The methods are demonstrated in simulations and applied to a rosiglitazone meta-analysis, yielding tighter inference and actionable conclusions about cross-study homogeneity and model selection in meta-analytic practice.
Abstract
In modern scientific research, small-scale studies with limited participants are increasingly common. However, interpreting individual outcomes can be challenging, making it standard practice to combine data across studies using random effects to draw broader scientific conclusions. In this work, we introduce an optimal methodology for assessing the goodness of fit of a reference distribution for the random effects arising from binomial counts. For meta-analyses, we also derive optimal tests to evaluate whether multiple studies are in agreement before pooling the data. In all cases, we prove that the proposed tests optimally distinguish null and alternative hypotheses separated in the 1-Wasserstein distance.
