Pilate

Football referees are unbiased, right? They would never be influenced by fans or football players, right? Well, according to a study football refs are often swayed by their surroundings. Michael Lopez, a researcher and statistician at Skidmore College in New York, led a study that referees are much more likely to make calls that favor the team whose coaches and players are on the sideline closest to the potential penalty.

Lopez analyzed five years of NFL games, including 1,400 penalty calls where the action happened close to one team's sideline or the other. One of the files he examined was whether referees called a late hit on a player. If one player is tackling another, you're allowed to do it while the opposing player is within bounds but not if he's out of bounds. But the bodies are usually flying into one another near a sideline. It's what's called a bang-bang play: it all happens so quickly and the refs have to make a judgment call.

Lopez measured how often these kinds of judgment calls go in favor of the team whose coaches are on the sideline closest to where the potential penalty is taking place. He found referees are much more likely to make calls that comply with what people nearest to them are demanding. In short, intimidation works. Pressure the refs, get in their face, and they will often cave into social pressure.

Sports fans around the world can rely on one fact about their sport: the home team wins more often than the visiting team. A 2011 Sports Illustrated article concludes: "Home field advantage is no myth. Indisputably, it exists …. Across all sports and at all levels, from Japanese baseball to Brazilian soccer to the NFL, the team hosting a game wins more often than not." What explains this fact?

A wealth of evidence disputes the most common theories behind home team advantage. For instance, thousands of cheering or jeering fans didn't change a team's performance. On a number of statistics—such as pitch velocity in baseball or free throw percentage in basketball (which over two decades was 75.9 percent for home and visiting teams)—home field advantage didn't make a difference. Their research also eliminated other likely theories based on the rigors of travel for the visiting team or the home team's familiarity with their field, rink, or court.

So what drives home field advantage? According to the authors of the article, "Officials' bias is the most significant contribution to home field advantage." In short, the refs don't like to get booed. So when the game gets close, they call fewer fouls or penalties against the home team; or they call more strikes against visiting batters. Larger and louder fans really do influence the calls from the officials. The refs naturally (and often unconsciously) respond to the pressure from the crowd. Then they try to please the angry fans and make the calls that will lessen the pain of crowd disapproval. In the end, the refs' people-pleasing response can have an impact on the final result of the game.