Most people think horse racing is a game of prediction. It isn’t — not profitably. It’s a game of overlays, and the profitable operator is the one who finds runners whose true win probability exceeds the pool-implied price after takeout. Our job in this module is to do that hunt at scale.
The value ratio
Every target carries a single headline number: value_ratio = p_fair / p_implied. A value_ratio of 1.25 means our estimated probability is 25% higher than the market’s implied probability. On Betfair Exchange (low commission) we fire at 1.20+; on tote pools (17–25% takeout) we need 1.35+. Below those thresholds, the paper-thin edge is eaten by variance.
What the scanner considers
- Class and form. Last 6 runs, trouble-in-running codes, class-up/class-down moves.
- Speed figures. Beyer, TimeForm, RPR, Thoro-Graph — whatever the data feed provides, averaged over the last 3 with the ceiling flagged separately.
- Pace. Running style (E / E/P / P / S), pace pressure, lone-speed setups.
- Trainer angles. First-time starters, 2nd start off layoff, blinkers-on, claim-and-run.
- Jockey factors. Course win%, apprentice weight allowance, trainer-jockey combo stats.
- Track bias. 14-day rolling read of rail bias, speed bias, closer bias.
- Going. Surface preference via sire / dam-sire breeding, wet-track AEI.
- Equipment & meds. Blinkers on/off, Lasix L1 (US), tongue-tie, first-time gelding.
Free vs paid mode
Paid mode runs The Racing API (~£25/mo, UK+IRE+AU+HK+USA). Free mode falls back to Betfair Exchange delayed (free from Betfair developer portal) and runs exchange-vs-SP arbs. Free mode is narrower but zero-cost; paid mode is full handicapping. The setup wizard nudges you toward paid mode only if you check the advanced toggle.
Staking
Every target is staked at quarter-Kelly, capped at 3% of bankroll per race. If the fair-price estimate gives a negative Kelly (rare but happens when conviction is low), the target is rejected outright — no “sentimental punt” stake of 0.5% on a hopeful longshot. The skill doc is allergic to hopeful longshots.