Which Devig Method Should You Use?
Devig one market four ways and you get four different fair prices. On +650/−900 the answers are +675, +757, +757 and +815. That's a 140-point spread, easily the difference between "fire" and "pass." None of the formulas is lying. They just disagree about where the book hides its cut.
The four, in one breath each
Multiplicative shaves every side by the same ratio. Clean and standard, but it assumes longshots carry no extra juice, which decades of closing-line data say is wrong. Trust it on near-even spreads and totals. Additive takes an equal bite of raw probability from each side, which lands proportionally harder on the longshot. Good for moderate favorites. Power fits an exponent to the whole market and is the harshest on longshots: our +650 becomes +815. Reach for it on heavy chalk, alt lines and props. Shin models a book defending itself against insider money. On any two-way market it lands exactly on additive; on multi-ways it splits the difference (in a +100/+200/+280 market, the +280 longshot devigs to +333 additive, +328 Shin, +317 multiplicative).
The honest answer: stop picking
The Actual Odds default runs all four and headlines the stingiest one, labeled with the method that produced it: worst case (Power) and so on. The logic is simple. If a play is +EV under the most pessimistic devig, it's +EV, full stop. If it's only green under the friendliest method, you're not betting an edge, you're betting a formula choice.
Watch it work
Take +275/−350 boosted to +350. Multiplicative says fair +292 and +14.9% EV. Worst-case (power) says fair +319 and +7.3% EV. Both green: fire with confidence. When the two disagree on the verdict itself, the worst case just saved you a bad bet.