The favourite-longshot bias is one of the oldest and most stubborn findings in betting markets: longshots are systematically worse value than favourites. Bettors overpay for the dream of a big payout, and bookmakers — knowing this — load a disproportionate share of their margin onto high odds.
The sizes are not subtle. Across decades of studies, heavy favourites return a few percent below fair value, while extreme longshots can cost bettors 20% or more per bet. A 15.00 outsider quoted by a soft bookmaker might carry a true probability closer to odds of 20.00 — you are paying a hidden fee of a quarter of the price.
This has a practical consequence for reading any naive value model: divide a market's overround equally across outcomes and longshots will constantly look like value when they are anything but. Serious devigging must remove margin proportionally more from the outsiders — ours does, and it kills most of the phantom edges cheap models flag on high odds.
It also explains a tipster classic: the accumulator of longshots. Every leg quietly overpriced against you, multiplied together into a ticket whose advertised payout wildly overstates its worth. The dream is real; the price of the dream is rigged.
See how we apply this on every match in our methodology. Methodology →
Bookmaker margin (vig) and devigging Why win rate misleads Fair odds
See these ideas at work in our public track record — every call logged before kick-off, losses included.