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How Arbs works
Arbs research desk · Updated 2026-11-01 · Reviewed 2026-11-01 · 2 min read
The short answer: Arbs prices every game with its own model and shows that fair probability next to the live Polymarket price. Picks are locked before kickoff with a content hash, graded once from Polymarket’s resolution, and every result stays on the public record.
Inputs
- Sportsbook prices from The Odds API, Kalshi, and the book ESPN relays, with the margin removed: the power method on two-way lines, Shin’s method on three-way soccer lines
- Team records, recent form, ratings, rest, injuries and lineups
- Live Polymarket prices, order books, trades and each market’s fee schedule, which the model is measured against
The model
Devigged venue prices are combined into a consensus in log-odds, weighted by venue and by how fresh each quote is. Each quote’s weight decays with a 90-minute time constant:
pooled logit = Σ wᵢ × e^(−Δtᵢ ÷ 90) × logit(pᵢ) ÷ Σ wᵢ × e^(−Δtᵢ ÷ 90)
A team-records prior is pooled in, and a calibration step fitted on graded picks keeps the output honest: games priced at 60% should win about 60% of the time. Polymarket is not an input when enough venues price the game, because Polymarket is the price the model is trying to beat. When too few venues price a game, the board says so and no pick is made.
An AI judge reads the news and may move the quant probability by at most 6 points. It never sees the Polymarket price. The AI read on each game explains the number; it does not choose the pick.
From a number to a pick
A pick is not taken on the model’s number alone. Its EV is measured on Polymarket’s price moved part of the way toward ours, by a weight w fitted per league on graded games:
logit(p) = logit(Polymarket) + w × (logit(ours) − logit(Polymarket))
A league is picked only when that blend beat Polymarket’s own price on the newest graded games. Polymarket’s taker fee is netted out before anything is called an edge:
EV = p ÷ c − 1 must be at least 2%, where c is the ask plus its fee, and the ask must be at least 20¢
Locking and grading
- Ten minutes before the start each pick is locked: the probability, the market price and a content hash are written once and never edited
- After the game the pick is graded once from Polymarket’s resolution
- Losses stay up. A market Polymarket has not resolved two weeks after the start is marked void and left out of the totals
The win–loss record, return per unit and closing line value are on the track record, by league.
What Arbs is not
Arbs is a research tool for people 18 and older. It does not take bets, hold money or place orders. The numbers are estimates and can be wrong. See responsible gaming.
Frequently asked questions
Can Arbs change a pick after the game?
No. A locked pick is written once with a content hash. The grade is written once, only while the result is empty.
Where do the prices come from?
Polymarket’s public market data and sportsbook prices from The Odds API.
Is Arbs affiliated with Polymarket?
No. Arbs is independent and is not affiliated with Polymarket or any sportsbook.