Where the models live

A 4,000-game backtest across NFL, NBA, and EPL closing lines tests three vig-removal methods head to head. The power method outperforms multiplicative on lopsided markets; both beat additive on calibration. The dataset, the Python implementation, and the sport-by-sport CLV breakdown are here.

Wind speed dominates; rain barely moves the under. Ten seasons of NFL outdoor-game data on weather and total outcomes show that the casual bettor's mental model — rain = under, snow = under, cold = under — survives about two-thirds of the scrutiny. The other third is instructive.