Contest Win Probabilities and Ability Calibration R package winning version 0.3.0 Solves the horse race problem in both directions. Infers relative ability from win probabilities (or betting dividends) for contests whose entrants share a common performance distribution, with dead heats handled exactly, by the lattice fixed-point algorithm of Cotton (2021) <doi:10.1137/19M1276261>. Also computes all N win probabilities of a factor-structured Gaussian race (multinomial probit with low-rank-plus-diagonal covariance) in one shared-lattice pass of O(Q*N*L) operations, and inverts observed shares to abilities by a damped Newton method with analytic slopes. A dependency-free base-R port of the reference python package 'winning'. Performances are times: lowest wins. Software Suggests: mvtnorm, testthat (>= 3.0.0) Peter Cotton <peter.cotton@microprediction.com> Comprehensive R Archive Network (CRAN) Peter Cotton [aut, cre] MIT + file LICENSE (https://CRAN.R-project.org/package=winning/LICENSE) 2026-09-09 application/tgz https://CRAN.R-project.org/package=winning doi:10.32614/CRAN.package.winning