20

Inspired by this question but hopefully different enough to warrant a different question.

I often hear fans complaining that the "home team always gets the calls", which means that more fouls are called against the away team than the home team. This has been attributed to a number of things:

  • The emotion in the arena sways the officials
  • The home team coaches have longer conversations with the referees before the beginning of the game, and they are instructed on what types of fouls to watch for.
  • The referees, or the sideline replay officials, are natives of the home town and want their team to win.
  • The referees are paid money to make calls for the home team.

First question is: Does the home team actually get more favorable calls from the officials? Statistical research would be nice.

Second question is: If the home team gets more calls, are any of these specific complaints (or others) valid or verifiable by research?

We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.

  • 1
    I think this is a great answer is the answers can remain objective. On the fact it looks rather subjective, but there have been objective studies done on this subject. – wax eagle Feb 10 '12 at 16:23
  • This is not a constructive question. – Dynamic Feb 10 '12 at 19:58
  • @Jae can you help me understand why you feel that way? Or start a discussion in meta? – Marcus Swope Feb 10 '12 at 20:17
  • Because it varies by referee. If he's not a fair guy, he'll side with one team. It depends, therefor it is not a constructive question. – Dynamic Feb 10 '12 at 20:25
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    @Jae I understand that, but the question is regarding statistical research about the subject. Should all questions regarding batting average be considered not constructive because all batters are different? – Marcus Swope Feb 10 '12 at 23:40
15

I came across many articles with summaries of studies that indicate that referee bias does in fact exist across many sports.

In "Basketball: Bias Refs (full article)," the blurb states:

The study found that the probability of a foul call being against a visiting team was seven percent higher than calls against the home team. They also noted when the home team is ahead in the game, the likelihood of a foul being called against them is 6.3 percentage points higher than when they were behind. Finally, economists observed the larger the foul difference between the two teams, the more likely it is the next call will be made against the team with fewer fouls.

Gail Imber notes in his article "Referee Bias: Quantifying the Homer Effect and Officiating Home-Field Advantage":

Specifically, Boyko postulates that "While subconscious referee bias does not necessarily make home advantage unfair, our finding of significant variation in home advantage by referee is hard to accept as fair."

and

All verifiable studies decidedly concluded the "homey effect" is due to subconscious variations in play calling—not due to a conscious attempt to manipulate or "throw" the game.

There are links to several studies and articles in Imber's article. Some interesting excerpts:

  1. "Nevill asked qualified soccer referees to analyze various challenges which had been recorded on videotape, either with or without sound. Nevill found that when the variable of crowd noise was introduced, the referees called 15.5 percent fewer fouls against the home team.";
  2. "The Los Angeles Times' Douglas Farmer summed it up as 'subconscious submission to peer pressure.'"

In the blog post titled "More evidence for referee bias in soccer," Phil Birnbaum points to two studies related to European football - in the Spanish and German leagues. He notes:

Looking at games in the Primera Division in Spain over two specific seasons (1994-95 and 1998-99), they found that, in games where the score difference was exactly one goal, referees awarded almost twice as much extra time when the home team was trailing as when it was leading. More time, of course, benefits whichever team is behind, as it gives them a better chance to tie the game.

and

Also, the authors note that a German magazine, "Kicker Sportmagazin," reviews all games and posts an opinion on which penalty calls were correct and which were incorrect (both actual and missed calls). It turns out that for penalties called in favor of the home team, 5 out of 55 were illegitimate. But for visiting teams, it was only 1 out of 21. So referees favored the home team by about twice as many false positives.

False negatives also favored the home team. There were 12 cases where home team should have been awarded a penalty, but wasn't; there were 19 such cases for the visiting team.

In an article about NBA referees, James Downie notes:

They found "evidence of three biases: favoritism of home teams, teams losing during games, and teams that are behind in a multi-game playoff series. All three biases are plausibly profit-enhancing for the league." The authors calculate that, during the regular season, the turnover biases "equates to win probability changing by approximately 2.2% when a team switches from away to home status," and a further 2.5% if fouls are included. In the playoffs, the biases do not appear to affect fouls, but the effect on turnovers becomes nearly doubles, keeping the probability change close to 5%. Maybe beating that 5% is why coaches ask players to give 110%...

So in summary, it appears that referees across all sports do show some subconscious favoritism towards the home team, even while striving to remain impartial.

EDIT: Added some excerpts mentioned in one of my comments below.

  • This is a great answer to the first question, but did you come across anything that explained why they have this bias? I saw some references to it being a subconscious thing, but I am also curious as to what causes this. – Marcus Swope Feb 10 '12 at 18:47
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    Yes, some excerpts that I saw indicated that crowd noise/peer pressure contributed to this effect: 1. "Nevill asked qualified soccer referees to analyze various challenges which had been recorded on videotape, either with or without sound. Nevill found that when the variable of crowd noise was introduced, the referees called 15.5 percent fewer fouls against the home team."; 2. "The Los Angeles Times' Douglas Farmer summed it up as 'subconscious submission to peer pressure.'" – JW8 Feb 10 '12 at 19:51
  • That is actually very interesting, can you add it to the answer? – Marcus Swope Feb 10 '12 at 20:04
  • @MarcusSwope, comments added. Thanks for your feedback. – JW8 Feb 10 '12 at 22:03
  • the larger the foul difference between the two teams, the more likely it is the next call will be made against the team with fewer fouls. I'm guessing by "more likely" it means the likelihood is greater than when the margin is smaller, rather than fouls being more likely to be called against the fewer-fouls team than the more-fouls team, since the latter wouldn't make sense if the margin had been increasing. Confusing wording! On another note, I wonder if there's been any study of refs trained to be aware of possible influences on their decisions and whether such training works? – Matthew Read Feb 21 '12 at 23:25

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