the new bayesian methodology is sweet before, confidence intervals came from bootstrapping. now the method gives you a probability distribution for each model's ECI so you naturally get credible intervals and can ask questions like: "how likely is it that model A is stronger than model B?" it also bakes in better noise assumptions: - noise shrinks near 0% and 100%, so error bands no longer include impossible scores smaller 0% or greater 100% - and each benchmark gets its own noise level