Favourite-Longshot Bias

Favourite-longshot bias is the well-documented pattern in which betting markets underprice short-priced runners and overprice long-priced ones relative to their true chances. Punters systematically pay too much for the large payout a longshot promises, so outsiders as a group return worse than their odds suggest while favourites return better. It is one reason indiscriminate longshot betting loses money faster than backing favourites.