Custom devig & sharp books
The controls that drive Positive EV's fair price — picking a devig mode, choosing and weighting sharp books, requiring books, and setting a minimum number of sharps.
Two knobs, one fair price
The fair, no-vig price behind every +EV bet comes from two choices you control: the devig mode (the math used to remove a sharp book's margin) and the sharp books (which books feed the calculation, and how much each counts). For the concepts themselves, see Devigging & fair value and Sharp books. This page is about the knobs.
Choosing a devig mode
The Devig Mode filter offers five methods for converting a sharp book's two-sided odds into a single no-vig probability:
- Power — the default, and a reasonable middle ground for most markets.
- Multiplicative — splits the vig proportionally across outcomes.
- Additive — removes an equal share of the margin from each side.
- Probit — works on the normal-distribution scale, which can fit point-spread style markets.
- Worst — the most conservative; it takes the least favourable devigged price, shrinking borderline edges so fewer bets qualify.
Different methods produce slightly different fair prices, especially on lopsided lines. If a method consistently surfaces edges that vanish when you check the book, try a more conservative one.
The sharp-book menu
Opening the Sharp Books filter lists every eligible book with controls for how it participates:
- Required vs optional — the REQ. column marks a book as required (its price must be present for a market to qualify); the OPT. column adds it as a contributor without making it mandatory. Leave a book unchecked to exclude it entirely.
- Per-book weight — the weight control (the scale icon) sets how heavily a book pulls on the blended fair price relative to the others. A book set to 100 counts roughly twice as much as one set to 50.
- Per-book scope — the settings icon opens advanced options where a book can be scoped to specific sports or leagues, so it only anchors the markets it prices well.
- Min Sharps — the slider at the top sets the minimum number of contributing books a market needs before any bet on it qualifies. Raising it trades volume for confidence, since a price agreed on by several books is far less likely to be a one-off error.
Don't require books that don't price everything
Marking a book as required filters out every market it doesn't cover. An exchange that only prices major leagues, set to required, will silently empty your feed for everything else. Prefer optional plus a sensible Min Sharps.
A sensible starting point
The Recommended default weights the sharpest books most heavily, keeps everything optional, and sets a low Min Sharps. Positive EV also starts with Max Vig at 10%, which hides bets when the blended sharp prices carry a larger margin. You can adjust or clear that limit in Filters & settings.
Raise Min Sharps for more agreement, lower a noisy book's weight, or switch to the Worst devig mode as you learn which settings suit the markets you follow.
- 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.