Why do home teams win?

Author: Jim Albert

Image by Googie man via Wiki Commons

Everyone knows about the home team advantage in sports. For example, in my research in Curve Ball, I noted that 52% of the professional baseball games were won by the home team, and the game-winning percentages by the home team in professional football and basketball were respectively 58 and 66 percent. Athletes also generally perform better at home games compared to games played away from home. But the interesting question is: Why does a home field advantage exist?

Tobias Moskowitz and Jon Wertheim address this question in the fascinating article “What’s Really Behind Home Field Advantage?” that appeared in the January 17 issue of Sports Illustrated. (This article is taken from the new book Scorecasting: The Hidden Influences Behind How Sports Are Played and Games are Won by the same authors.)

Appropriate data is collected to address some of the “myths” about home field advantage. Many people believe home teams win since their crowds boost players’ performance, but the authors give evidence that the crowd doesn’t have an influence on home team performance. Other “myths” are that home teams win because the rigors of travel hurt the visitors and the home teams benefit from a kinder, gentle, schedule. But there is no evidence from data that these beliefs are true. Another popular belief that is refuted is that home teams benefit from unique characteristics of the home playing field.

Okay, so what is really behind home field advantage? The authors claim that there is a general referee bias to favor the home team in sports. This claim is supported by several studies. In baseball, the umpire will decide if a pitched ball is a strike (inside the strike zone) or a ball (outside of the strike zone). Home team hitters are less likely to have a pitched ball called strike than the visiting team hitters. Likewise, home team players generally have an advantage in stealing a base, and scoring from second base on a single base hit. Also, interestingly, the home team bias is larger when the particular play is more important in deciding the outcome of the game.

This referee bias carries over to other sports. In soccer, in close games when the home team was ahead, the referees had a tendency of reducing the length of the allotted extra time to make up for lost time (the so-called stoppage time). In American football, the away team is more likely to receive penalties and the size of the bias increases in more crucial situations that impact the game outcome.

Are the referees deliberately favoring the home team? The authors think not. They believe that the umpires are (like all of us) susceptible to social pressure, which in this case is the home crowd, and this social pressure causes the bias.

This is interesting stuff and I’m interested in doing my own data exploration to learn more about the home advantage in sports. But certainly this study has implications on how referees are trained or chosen in sports.

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Ricardo Montolivo

it can't just be a matter of refereeing bias, because the stats are plain and simple. i analyse soccer mostly and see incredible runs of coincidence where the home team has a great number of wins on a particular opponent. i believe that many things determine this, i do believe the crowd has a significant impact. the adrenaline they can register on players has an effect. also there is a theory that players playing at home have more of a need to defend their territory and so their testosterone levels are far higher playing on home games, which helps in physical sports such as american football or field soccer. i believe this to be true. there is also the fact of being in familiar surroundings which helps with cortisol levels. being an away team will automatically spike those, and combined with the testosterone differences, it can have a marked effect on performance. i am trying to find some other possible factors one other possible thing here. the fact of girls watching guys can also boost their testosterone. soccer teams like rosenborg who have a large number of female followers have generally an incredible home record, something like 70% winning record. it may sound stupid and it may actually be stupid, but you never know :)

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Our research into the new Pitch f/x data shows that about 70% of the home field advantage in baseball is due to umpire bias in ball/strike calls. Much of rest occurs on ground balls, indicating that familiarity with your own infield's grass (and dirt) plays a role. http://www.sportsmogul.com

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this article contradicts itself.
Qoue "They believe that the umpires are (like all of us) susceptible to social pressure, which in this case is the home crowd, and this social pressure causes the bias."

If this is true, than the referee (unintentionally) answers to the crowds' will, wich is that the home team must win. This means the opposing teams players must also be affected by social pressure and therefor perform less good. Leading to the final conclusion that the home team will also be affected by the social pressure, causing them to play better.
Thus the first myth in your article is false.

Btw crowds inducing xtra performance to players is in no way a myth, just ask any sporter about the feeling they get when 50.000 people are yelling your name. nuff said, but 1 more thing: it has been scientifically proven that when you are in the spotlight performing, you generate more dopamine, adrenaline and another compound from which i forgot the name... all off them cause you to perform better.

The reason behind this, is because when hunting only 1 person could get the kill, and the kill would get you wealth, wives and such and thus your body had to be at his absolute best to perform.

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