Kelly criterion
A formula for how much of a bankroll to stake on a positive-EV bet.
Kelly staking sizes a bet in proportion to the edge the model believes it has over the market. Larger edge, larger stake; no edge, no bet. Betting more than Kelly suggests increases the risk of ruin without increasing long-run growth.
Where RaceModel shows a Kelly fraction it is the full-Kelly figure. Most practitioners stake a fraction of it because the model's probabilities carry their own uncertainty.