A sportsbook is a business that accepts wagers and pays out winning bettors. It profits by charging a small fee on losing bets, while collecting vig on winning wagers. There are many ways to find a sportsbook, including online betting exchanges. However, there are a few important things to keep in mind when selecting an online sportsbook.

Among the most popular sports betting markets are point spreads and totals, which aim to level the playing field for underdog teams. These oddsmakers work hard to consider home/away performances, injuries and other news that could affect a team’s performance. They also try to balance action and reduce liabilities by moving betting lines as the situation develops.

The statistical framework used here to evaluate the accuracy of sportsbook prices is a conditional expectation that takes advantage of the marginal distribution function of the margin of victory. Theoretical treatment is complemented with empirical results from over 5000 matches from the National Football League that instantiate the derived propositions and shed light onto how close sportsbook estimates must deviate from their theoretical optima to permit positive expected profit.

A new upper bound is derived for the minimum error rate, and it is shown that a bettor should always bet against the sportsbook if the proposed spread or total deviates by more than this amount. It is further demonstrated that the maximum expected value of a unit bet, when wagered against the sportsbook, can be approximated by the median of the conditional expectations.