Sportsbook Point Spreads and Margin of Victory


A sportsbook is a gambling establishment that accepts bets on various sporting events. Traditionally, sportsbooks only allowed bets on football, basketball, baseball, and hockey games, but they have since expanded to include a variety of other events. Sports betting was banned across the US until 1992, when the Professional and Amateur Sports Protection Act permitted sportsbooks to open.

Many states have legalized sportsbooks, but the field is still relatively young. It is important to research local gambling laws and responsibly gamble. Also, make sure to gamble only with money that you can afford to lose and never place a bet with more than 10% of your total bankroll.

The purpose of this paper is to analyze the adequacy of sportsbook point spreads by estimating quantiles of the distribution of the margin of victory and points totals from heterogeneous data. The data were stratified into 21 groups based on the relative strength of the home and visiting teams. For each group, the mean and standard deviation of the margin of victory were computed for both teams, enabling the estimation of the 0.476 and 0.524 quantiles in the distribution.

The results show that the sportsbooks estimate the median margin of victory and point totals within 2.4 percentiles of the true values. This is well below the minimum error rate required to permit a positive expected profit when wagering on one side of the line. In addition, the analysis reveals that sportsbooks may sometimes propose spreads that deviate from their estimated median in order to entice a preponderance of bets on the side that maximizes excess error.