How our numbers work

1. Where the odds come from

We collect public sportsbook golf-board data several times an hour during tournament weeks. For selected major-championship coverage, we also use our configured odds-data API. Every price carries a timestamp, and every change is appended to a permanent history archive, which is what powers the movement sparklines and “market movers” modules. You can see exactly how fresh each book’s data is, at any time, on our transparency page.

Staleness rule: if a book’s price for a market is more than 36 hours old, it is dropped from the grid entirely. We would rather show fewer books than a wrong price.

Sportsbooks and prediction markets: we also list outright-winner prices from prediction markets (Kalshi, Polymarket) as their own columns, and they’re eligible for the best price. Because their exchange prices reflect order-book liquidity rather than a bookmaker’s margin, they are excluded from the de-vigged fair line — the fair % and edge are built from sportsbooks only.

2. Best price

For every golfer we simply highlight the longest (highest-paying) price across the books we track. No judgement involved — it’s arithmetic. In deep golf fields the same player is routinely priced 20–40% apart between books, which is why line shopping matters more in golf than in any spread sport.

3. Removing the bookmaker margin (de-vigging)

A bookmaker’s implied probabilities always add up to more than 100% — the excess is their margin (the “vig” or “overround”). A simple two-sided example: a coin-flip market priced at −110 / −110 implies 52.4% + 52.4% = 104.8%. Dividing each implied probability by the total recovers the fair 50/50.

We apply the same proportional method to every book’s full golf board. Full-field golf outright markets commonly carry overrounds of 120–140%, so raw implied probabilities dramatically overstate every golfer’s chance — de-vigging is essential before any comparison of “value” means anything.

4. The weighted fair line

Each book’s de-vigged board is an opinion about every golfer’s chance. We blend those opinions into a single consensus, with weights reflecting the source type and expected market efficiency. Only active sportsbooks contribute, and a book must price at least two golfers in a market — a single quote can’t be de-vigged. Finally we renormalize across the field so the probabilities sum to 100%, giving the fair % you see in the grid.

5. Edge

Edge is the expected value of the best available price measured against the fair line: edge = (best decimal price × fair probability − 1) × 100%. A positive edge means the best book is paying more than the market consensus says the golfer’s chance is worth. Because golf overrounds are large, genuine positive edges on outrights are rare — which is exactly why we show the honest number instead of manufacturing “value picks”.

6. Each-way terms

Where a book settles golf outrights each-way, we track its published place terms (fraction and number of places, including extra places on majors) per event and show them next to the grid. US-style books expose separate Top 5 / Top 10 / Top 20 markets instead — we compare those as their own markets.

7. What we don’t do

• No affiliate links, tracked redirects, or paid placement — see the independence note below.
• No proprietary prediction model dressed up as truth: our fair line is derived from market prices only.
• No republishing of third-party models or paid data feeds.
• No betting advice. We show prices, fair-odds context and movement; what you do with it is yours.