Is Home Field Advantage is a Myth?
On September 1, Dirk Chatelain of the Omaha World-Herald wrote an article that somehow I missed at the time, but noticed when he retweeted this on Saturday, October 15th.
#B1G road teams went 6-0 today. I can't wait to see the numbers at season's end.https://t.co/ivg3N3NEG6— Dirk Chatelain (@dirkchatelain) October 16, 2016
Dirk maintains that home field advantage in college football isn’t a thing anymore because road teams are winning more than they used to.
Considering only the winning percentage of home and away teams doesn’t address the fundamental question...Does playing at home impact how a team plays? For example, if OSU plays Purdue, they might be favored by 30 points on a neutral field. What does OSU beating Purdue on the road by 23 mean?
OSU would beat Purdue 98 times out of 100 this year, so is winning on the road anything to raise an eyebrow at? When you consider only winning percentage, and not whether being on the road or at home affected the score, you get answers to the wrong question.
Objective versus Subjective Measures
It is possible to directly measure a team's performance on the road versus at home, and quantify the differences in performance. By doing so, there’s no need to imagine subjective rationales for why home field advantage is meaningless now.
Because it’s not meaningless. Teams play better at home. They score more points at home than they do on the road. They allow fewer points on defense at home than they do on the road. The fumble less and rush for more yards at home.
I looked at multiple offense and defense statistical categories, and ALL showed the same general pattern: Team play better at home. For simplicity’s sake, I’ll look at just four categories in this article. The numbers I use in this article are only from FBS-vs-FBS games, and I only considered games 5-15 in order to approximate conference games and to eliminate the effect of ‘cupcake’ games many Power-5 teams play.
Using data from 2008 through last October 15th, 2016, I found that teams scored, on average, 11.7% fewer points on the road than they do at home. Only 16 of 130 teams averaged more points on the road than they did at home. Nebraska was one of these teams, averaging 27.4 at home and 28.9 on the road.
Teams allowed, on average, 14.0% more points on defense on the road than at home. Again, only 16 teams (not all the same ones) allowed fewer points on the road. Oregon State was one of these 16, allowing 29.1 points at home and 28.9 on the road.
Teams rushed, on average, for 7.3% more yards at home than on the road. 34 of 130 teams rushed for more yards on the road. Nebraska rushed for an average of 190.7 yards at home and 187.5 yards on the road.
Teams committed, on average, 6.2% more turnovers on the road than at home. This statistic was not as affected by playing away from home as much as the others, with 51 of 130 teams committing fewer turnovers on the road than at home. Nebraska was one of these teams, committing on average 3.24 TOs per game at home and 3.05 TOs per game on the road.
What About Last Week?
Dirk had a fair point. Road teams in the Big Ten went 6-0 last week. Does this portend the death of the home field advantage? Let’s break it down and see.
- Minnesota beat Maryland 31-10
- Illinois beat Rutgers 24-17
- Iowa beat Purdue 49-35
- Northwestern beat Michigan State 54-40
- Nebraska beat Indiana 27-22
- Ohio State beat Wisconsin 30-23
Which of these road wins was an upset? I don’t like to make subjective arguments, but I think it’s reasonable to say than none of them are, and certainly none of the results is shocking in the way that Purdue over Ohio State would be.
Dig Into the Data. Decide for Yourself.
I built a visualization that includes all this data for the entire FBS. Poke around and decide for yourself whether playing at home makes a difference.
The gray bars represent a team’s average performance at home over the selected time period. The red marker indicates a road average. For offensive stats (scoring offense and rushing) the red marker usually overlaps the bar, meaning that the team scored fewer points or rushed for fewer yards on the road. For scoring defense and turnovers, the red markers are usually above the bar, meaning that the team allowed more points or committed more turnovers on the road. You can add in the games I removed (1-4) to see the effect of non-conference play as well.
Winning percentage is a bad way to judge whether home field advantage exists. Winning or losing is a secondary statistic based on how many points a team scores and how many it hold an opponent to. Additionally, it is basically useless as an indicator when one team is greatly overmatched. To more accurately measure the effect of home field advantage, statistics that directly capture a team’s performance should be used. When we do that, it is clear that home field advantage remains a large part of this wonderful game we call college football.
If you want to download and play with the data I used, you can download it here.