No referee bias in the NBA: New evidence with leagues’ assessment data

Beginning March 2015, the National Basketball Association (NBA) started the public assessment of officiated events in close game situations, where teams are within five points with two or less minutes to play. This ex-post league evaluation of officials’ actions allows for a much improved analysis of referee biases like the home bias, preferential treatment of superstars, race and favoritism towards losing teams. Instead of relying on statistical frequency of calls and devoting it to biased decision making, in-game decision making is matched with reviewed broadcasting video in this paper. The empirical analysis for 113 games and 1229 total calls finds no support of referee bias in foul calling.