Devigging & fair value
The five devig methods SmartStake offers — power, multiplicative, additive, probit, and worst — what each one does conceptually and when to reach for it.
Why method matters
Devigging is the act of removing a book's margin to recover the no-vig fair odds. There is no single correct way to do it, because the margin a book charges is not spread evenly across every outcome. Favourites and longshots carry the juice differently, and how you assume it is distributed changes the fair price you recover — and therefore the edge you compute. SmartStake makes the devig method user-selectable, with five approaches, so you can match the assumption to the market you are pricing.
The five methods
- Multiplicative — divides every implied probability by the market's total so they sum to 100%, scaling each outcome by the same factor. It is the simplest and fastest method and a sensible default for tight two-way markets where the juice is roughly symmetric.
- Additive — subtracts an equal slice of the margin from each outcome rather than scaling proportionally. It shifts probability toward longshots compared with multiplicative, and suits markets where you believe the hold is spread flat across outcomes.
- Power — solves for an exponent that makes the probabilities sum to 100%, which removes more margin from favourites and less from longshots. This better matches how books actually price many markets and is a strong general-purpose choice.
- Probit — works in the normal-distribution (z-score) space rather than directly on probabilities, which tends to handle the extremes — heavy favourites and long longshots — more gracefully than the proportional methods. Reach for it on lopsided markets.
- Worst — deliberately takes the least favourable fair estimate across methods, producing the most conservative price. Choosing it means you only see an edge when the bet looks +EV under even the harshest assumption, trading volume for confidence.
Conservative by default
If you are unsure, a more conservative method — power or worst — surfaces fewer bets but fewer false edges. Loosen toward multiplicative only once you trust a market.
Blending across books
Devigging a single book gives one estimate of fair value. SmartStake's real fair price blends the devigged prices from several books the market considers sharpest, which smooths out any one book's quirks. Which books count as sharp, how they are weighted, and how many must agree before a line qualifies are covered in Sharp books & why they're the benchmark.
- Odds, prices, expected value, conversion rates, and profit figures shown are estimates based on the last data we retrieved. They can change at any time — confirm the current price at the book before you bet, as odds may move and entry errors can occur.
- Using a “sharp” book as a fair-value reference is a modeling choice, not a statement of accuracy. Review a book’s record yourself and anchor on the books you trust.