Major League Baseball during the COVID-19 pandemic: does a lack of spectators affect home advantage?

A home advantage is present in most professional sports leagues. Spectators may be a major factor in home advantage, but empirical results have been mixed. Professional games were played without spectators during the 2020 season amid the COVID-19 pandemic. This study investigated home advantage in Major League Baseball (MLB) during 2020 as compared with the 2015-2019 seasons. A total of 13,044 regular-season games (898 in 2020 and 12,146 in 2015-2019) were analyzed. The sum of wins above replacement of all players was used as an indicator of team quality. The likelihood of a home-team win with spectators was not significantly different to that without spectators (odds ratio = 1.068; 95% confidence interval = 0.932-1.224, p > 0.05). The relative home advantage, percentage of home wins of total wins by a team in a specific season, was not significantly different across years, team quality, and attendance. Factorial analysis of variance models that included the variables of year, team quality, and attendance also revealed that none of these variables significantly affected the relative home advantage. The results suggest that spectators may not be an important factor of home advantage in MLB.