WORKSHOP ON RISK ANALYSIS AND APPLICATIONS
24 and 25 of SEPTEMBER, 2025
Institute of Mathematics and, Statistics of the University of São Paulo, Brazil
SATELLITE WORKSHOP OF
8th BRAZILIAN CONFERENCE ON STATISTICAL MODELING IN INSURANCE AND FINANCE
WORKSHOP ON RISK ANALYSIS AND APPLICATIONS
24 and 25 of SEPTEMBER, 2025
Institute of Mathematics and, Statistics of the University of São Paulo, Brazil
SATELLITE WORKSHOP OF
8th BRAZILIAN CONFERENCE ON STATISTICAL MODELING IN INSURANCE AND FINANCE
Title: Covariance balance under Bayesian decision theory
We study optimal sample allocation between treatment and control groups under Bayesian linear models. We derive an analytic expression for the Bayes risk, which depends jointly on sample size and covariate mean balance across groups. Under a flat conditional prior, the covariate mean balance term simplifies to the Mahalanobis distance. Our results reveal that the optimal allocation does not always correspond to equal sample sizes, and we provide sufficient conditions under which equal allocation is optimal. Finally, we extend the analysis to sequential settings with groups of patients arriving over time. (joint work with André Fumis and Rafael Stern)