"Football Freakonomics": How Advantageous Is Home-Field Advantage? And Why?

The following is a cross-post from NFL.com, where we’ve recently launched a Football Freakonomics Project.

Do home teams really have an advantage?

Absolutely. In their book Scorecasting, Toby Moskowitz and Jon Wertheim helpfully compile the percentage of home games won by teams in all the major sports. Some data sets go back further than others (MLB figures are since 1903; NFL figures are “only” from 1966, and MLS since 2002), but they are all large enough to be conclusive:

League Home Games Won
MLB 53.9%
NHL 55.7%
NFL 57.3%
NBA 60.5%
MLS 69.1%

So it’s hard to argue against the home-field advantage. In fact my Freakonomics co-author Steve Levitt once wrote an academic paper about the wisdom of betting (shh!) on home underdogs (more here).

But why does that advantage exist? There are a lot of theories to consider, including:

  • “Sleeping in your own bed” and “eating home cooking”
  • Better familiarity with the home field/court
  • Crowd support

Those all make sense, don’t they? In Scorecasting, Moskowitz and Wertheim compile data to test a variety of popular theories. You might be surprised (and maybe even disappointed) to read their conclusion:

When athletes are at home, they don’t seem to hit or pitch better in baseball … or pass better in football. The crowd doesn’t appear to be helping the home team or harming the visitors. We checked “the vicissitudes of travel” off the list. And although scheduling bias against the road team explains some of the home-field advantage, particularly in college sports, it’s irrelevant in many sports.

So if these popular explanations don’t have much explanatory power for home-field advantage, what does?

In a word: the refs. Moskowitz and Wertheim found that home teams essentially get slightly preferential treatment from the officials, whether it’s a called third strike in baseball or, in soccer, a foul that results in a penalty kick. (It’s worth noting that a soccer referee has more latitude to influence a game’s outcome than officials in other sports, which helps explain why the home-field advantage is greater in soccer, around the world, than in any other pro sport.)

Moskowitz and Wertheim also make clear, however, an important nuance: official bias is quite likely involuntary.

What does this mean? It means that officials don’t consciously decide to give the home team an advantage — but rather, being social creatures (and human beings) like the rest of us, they assimilate the emotion of the home crowd and, once in a while, make a call that makes a whole lot of close-by, noisy people very happy.

One of the most compelling (and cleverest) arguments in favor of this theory comes from a research paper by Thomas Dohmen about home-field advantage in Germany’s Bundesliga, the country’s top soccer league.

Dohmen found that home-field advantage was smaller in stadiums that happened to have a running track surrounding the soccer pitch, and larger in stadiums without a track.

Why?

Apparently, when the crowd sits closer to the field, the officials are more susceptible to getting caught up in the home-crowd emotion. Or, as Dohmen puts it:

The social atmosphere in the stadium leads referees into favoritism although being impartial is optimal for them to maximize their re-appointment probability.

So it looks like crowd support does matter – but not in the way you might have thought. Keep this in mind next time you’re shouting your brains out at a football game. Just make sure you know who you’re supposed to be shouting at.

 


Steevn

A simple metric to prove this would be " How many penalties per side, on average?"

For example, for the NFL, I want to see a stat showing me that the home team receives 9.3 penalty flags for 103.7 yards, while the visiting team receives 10.4 flags for 115.2 yards.

Can't somebody whip this out?

Mike

Based on data I've pulled, home teams average 6.1 penalties per game, while away teams average 6.5 penalties per game. So the data supports the video (although I have no idea why they didn't provide such a simple metric in the video itself - maybe it's a touchy subject for the NFL?).

However, I've found that most stats, including penalties, show a home team bias (passing yards per attempt, rushing yards per attempt, interception rate, fumble rate), so I'm not sure referee bias can explain all of home field advantage in football. Which leads me to favor Brian Burke's explanation: http://www.advancednflstats.com/2009/09/hawks-doves-and-home-field-advantage.html

triclops

In the NBA, stars usually do equally well at home and on the road. Many role players, however, shoot significantly better, and are generally more effective at home compared to the road.

Kurt

"Dohmen found that home-field advantage was smaller in stadiums that happened to have a running track surrounding the soccer pitch, and larger in stadiums without a track."

How causal is this link? Perhaps it goes the other way around. You only play in a stadium with a track around it, if you're financially (and on the field) less powerful...

Jason

In soccer, there's also the issue of differing field sizes. Soccer's pitch dimensions aren't consistent; MLS teams can pick several different sizes, and those sizes can influence the way teams play and/or defend. A smart manager (Tony Pulis at Stoke City, for instance) knows that his defensive team is better off playing on a short, narrow pitch, whereas a team like Barcelona will want to play on a wide open pitch with more area to defend.

That really does allow for a tangible difference between home and away matches; teams used to playing expansively may not be able to due to the physical restrictions in place at away venues.

Fred

In the playoffs at least, the cause and effect are reversed --

Thr home team wins more often because it is the stronger team, because the team with the better record gets to BE the home team in the first place.

Grace McNutt

Just wanted to say that this article helped me a lot with a science fair survey I was conducting. Thanks!

neil

Interesting speculation here that home field advantage for soccer in the English Premier League may partly result from home players winning a higher proportion of their personal one on one duels at home because of an elevated testosterone level that results from a feeling that they are defending their territory.Also links to a few of the usual referee bias theories.

http://thepowerofgoals.blogspot.com/2012/01/home-advantage-and-personal-duels-in.html

Barry Sherry

In my soccer pregame with my referee team I empathize the four game-critical calls we can make (1) Penalty Kick (2) Offside (3) Red Card (4) Goal/No-Goal decision. Red cards and PKs are relatively rare. The basketball ref has much more of a direct influence by hitting a star player with three early fouls. And in football, does anyone influence the game more than the ref who gives a pass interference spot penalty (NFL), in essence, a 50-60 yard penalty? I disagree with the statement that a soccer referee has more latitude to influence a game. But great article nonetheless.

Eddie Vega

Maybe because these players are pros. So the crowds, whether at home or on the road, don't affect them that much. But any of us mere mortals who's played sports especially as youths can tell you, whatever game you're playing, when you're on your own field, diamond, court, rink or pitch, you simply play better when the crowd are cheering FOR you and not against you. It's just as much human nature, as the assertion that refs would be swayed by the home crowd when making their calls. I read the book and the authors truly make good arguments everywhere, and the stats seem to show it. But I'd like to think that the home crowd DOES influence the home team to play better, the same way it does even for us non-professionals. Also, the tendency for sports leagues anyway is for the refs to always favor the stars. Whether it is the likes of John Elway, Wayne Gretzky, Pele, Nolan Ryan or Larry Bird before, or Tom Brady, LeBron James, Mike Trout, Sidney Crosby or David Villa today, the refs would always favor the stars, more than they favor the home team necessarily.

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