The betting market for the NHL is investigated using actual betting percentages on favorites and underdogs from real sportsbooks. Sportsbooks do not appear to attempt to price to balance the book as betting percentages are not proportional to set odds. As in the NFL and NBA, bettors are shown to have a strong preference for favorites and road favorites in particular. Simple strategies of betting against significant imbalances toward the favorite are shown to generate positive returns. Although not pricing to balance the book, sportsbooks do not appear to price to exploit known bettor biases in all cases. Clear bettor behavioral biases for road favorites are not priced into the odds as the prices set in these cases appear to be a forecast of game outcomes. Pricing as a forecast may ensure long-run viability for the sportsbook as it discourages entry into this market by informed traders and still allows the sportsbook to capture its commission on losing bets over time.
JEL Classification G1The unearthing of actual betting data from real sportsbooks has allowed a more complete investigation of how sportsbooks truly set prices and, more importantly, has deepened our understanding of efficient markets, or lack thereof, within this market. Under the traditional models of sportsbook behavior, such as Pankoff (1968), Zuber et al. (1985), and Sauer et al. (1988), sportsbooks were assumed to set a market-clearing price by balancing the book. This price would split the betting action between both sides of the wagering proposition. Setting prices which balance the book allows sportsbooks to earn risk free returns when wagering balance is achieved, with sportsbooks earning their commission (under an 11-to-win-10 betting rule) on losing bets. Given that the observed price was assumed to be a result of the actions of bettors, sports betting markets became a natural place to test the efficient markets hypothesis. Findings in support of the efficient markets hypothesis within these wagering markets, where public sentiment is likely to run extremely high, served as a significant stamp of approval of this theory and supported the notion of the general "Wisdom of Crowds".Levitt (2004) challenged the traditional models of sportsbook behavior. His hypothesis assumes sportsbooks set prices to maximize profits, rather than setting prices to balance the book. Through the use of data from a betting tournament for the NFL, Levitt showed that bettors tend to prefer certain wagers, such as road favorites, and sportsbooks incorporate these known bettor biases into prices. With biased prices, sportsbooks earn higher profits by becoming an active participant in the wager, effectively wagering on the less-popular side of the proposition. Under the Levitt hypothesis, sportsbooks are not only good at forecasting game outcomes, but also know the likely biases of bettors, and are able to exploit these advantages through their pricing.One problem with the study of Levitt (2004) was the use of a betting tournament rather than data from an actual sport...