All-star Fans and Home Court Advantage

By Kieran Allsop and Scott Ganz

Abstract

The existence of a home court advantage is one of the most durable empirical patterns in all of sports. Yet, the sociological and psychological mechanisms explaining its strength and persistence remain a mystery in large part because of well-known challenges with statistical identification. We use crowd-size restrictions in place during the 2020-21 National Basketball Association regular season as an instrument in order to identify the effect of crowds and crowd size on home court advantage. We show that home teams win by 2.13 points, on average, when fans are present at games compared with 0.39 points when no fans are present. This is approximately the same impact as replacing a league-average player with an all star. In fixed effects instrumental variables regression models, we estimate that each additional one thousand fans generate a home court advantage of approximately 1.4 points. We conclude that the presence of home fans, on its own, explains a larger share of home court advantage than previously thought.

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