Officiating bias: The effect of foul differential on foul calls in NCAA basketball

In this study, we examined the pattern of foul calls exhibited during 365 NCAA basketball games during the 2004-2005 season. Results of the analysis indicate that officials are more likely to call fouls on the team with the fewest fouls, making it likely that the number of fouls will tend to even out during the game. This increased probability increases as the foul differential increases. In addition, there is a significant bias towards officials calling more fouls on the visiting team, and a bias towards foul calls on the team that is leading. The result is that the probability of the next foul being called on the visiting team can reach as high as 0.70. Finally, the implications of this officiating bias are explored, including the fact that basketball teams have an incentive to play more aggressively, leading to more physical play over time.