In Reply to: Re: Rutgers has the best statistical home court adv. in the B1G... posted by UCLART on February 13, 2025 at 17:27:52
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"Who has the largest home-court advantage in college basketball? How many points is it worth? Well, I have some bad news for you: It is really impossible to answer these questions with much precision. We can look at the box score of a game and see how many points a team won by or how many points each player scored.
Maybe one could do a little more fancy maths and make an estimate on what each player contributed to the point total. But we can’t tell how many points the home court contributed. Maybe someday, but for the most part people don’t care as much about the value of home-court as they do about the value of a star player. So that’s where the research focus lies.
But it’s a fun analytic exercise to try determine the value of home-court. I’ve been thinking about it for a while, starting a few years ago I wrote this article about home-court advantage at ESPN. The analysis was rather primitive and I apologize to everyone for paying their hard-earned Insider money for that. Basically, it identified the teams that had the largest difference between their home and road scoring-margin in conference play. Those teams probably had the largest home-court advantage, right?
For instance, from 2002-2009, Texas Tech outscored its opponents by an average of 6.0 points in conference games in Lubbock and were outscored by 9.3 points per conference game on the road. The difference of 15.3 suggests a home-court advantage of 7.6 points per game relative to a neutral court. That figure was the highest among 320 teams that played at least 50 conference games over that time.
If we could go back to 2009, maybe I could convince you that United Supermarkets Arena, or whatever it was called then, was one of the most difficult places to play. But accepting that the Red Raiders’ home floor was worth close to eight points seems beyond the bounds of a legitimate home-court advantage value.
And that tells you that this method doesn’t really measure home-court advantage. To be precise, the 7.6 points represents how much better a team played in home games than road games. Or even more precisely, that figure is the difference between home and road scoring margin. To a large extent we should expect that number to reflect the difference in a team’s play between home and road venues. We should also expect the difference in a team’s play to reasonably reflect the value of home-court if we’re controlling for quality of competition.
And since we’re only considering conference games, we are controlling for the quality of competition. Over enough games – Texas Tech played 64 games each on the road and at home over those eight seasons – random noise should be minimized. The Red Raiders could have had a strong home-court advantage but also benefitted from a few more breaks at home. Maybe they caught teams on especially bad nights or maybe they had their best games at home. Going forward I’ll put quotes around “home-court advantage” when referring to this measure because it’s really measuring actual home-court advantage plus some amount of noise.
The average team had a “home-court advantage” of 3.75 points per game over this time period. Home much of an advantage would the team with the best home-court have? This is an interesting question. One way to get an idea is to try and make predictions.
If that 7.6 points per game were real, we’d see something close to that going forward. But over the next eight seasons, from 2010-2017, Texas Tech had a “home-court advantage” of just 4.0 points. That is still easily above the national average, but the point is it’s a serious drop from what was observed over the original 64 games. That’s not surprising considering that almost any time a team or player is leading some statistical category it is the product of skill and good fortune, and some level of regression to the mean is right around the corner.
There seems to be a lot of good fortune for teams that led the country in “home-court advantage” from 2002 to 2009. Of the 50 teams that had the best “HCA” in the first period, 48 of them had a worse “HCA” in the second period we’re looking at. In fairness, home-court advantage has been decreasing across the country as a whole in recent years. The average over the second eight-year period was a half-point lower than the first. Still, 45 of the 50 had a worse “home-court advantage” relative to the average “HCA” of each period...
"In our last installment, we discussed the degree to which past home-scoring advantage predicts future home-scoring advantage. We can look at other stats and derive home advantages from them. For an example, let’s use home steals advantage. Like home-scoring advantage, this is the difference between a team’s home steal margin and road margin.
In conference games from 2002-2009, Alabama averaged 1.32 more steals than their opponents at home and averaged 1.98 fewer steals than their opponents on the road. That gives a home-steals advantage of 1.66, which led all teams during that time.
Does home-steals advantage predict future home-scoring advantage? Well, no, not at all. And most box-score stats don’t. But there is one stat that actually outperforms points. If we just use home-foul advantage by itself to predict future “home-court advantage”, it does significantly better than home-scoring advantage...
"It’s not a huge difference, but our cloud of data points is getting stretched out along the line of perfect predictions a little bit. Of course, using both home-foul advantage and home-scoring advantage is even better to predict future home-court advantage...
"So it’s pretty clear that fouls drive home-court advantage more than any other thing recorded in the box score. Another piece of evidence that foul bias is an important source of home-court advantage is the identical trend in home-court advantage and home-foul advantage over the past decade-and-a-half...
"As far as what’s causing the decrease in home-foul advantage, one can only speculate. As officials and their supervisors get more and quicker access to video from games, it stands to reason that they would become more fair about making calls. But it’s also possible that less enthusiastic fan support may be decreasing the home crowd’s influence on officials. Or players themselves may be more prepared in road games than they used to be for some reason. Whatever the source, the result appears to be a fairer whistle towards the road team.
The next step is to make predictions for the home-court advantage of each team. So far, I’ve been using eight years of training data and eight years of target data. It obviously helps to have more seasons to stabilize some of the data, but just using half of our 16-year sample to predict the other half limits us to 325 data points. We could use the previous two years to predict the next season of home-court advantage. This has the drawback of increasing the error of predictions, but it has the benefit of increasing our sample by a factor of 15.
After considerable experimentation, I’m using the past six seasons of data for each team to predict its next two seasons of home-court advantage. This gives the value for each some stability while allowing flexibility for home-court numbers to change over time.
The increase in samples for the model revealed two other stats of importance: non-steal turnovers and blocks. Home advantages in both of those categories influence the model as well. And finally, a team’s elevation is included in the model.
I must warn you that any predictions of team-specific home-court advantage will be noisy. I mean, just look at the plot of predicted vs. actual HCA based on home-foul and home-scoring advantage. A lot of those points stray pretty far from the line of perfect predictions. And those are in-sample predictions. Any predictions for the next few years will undoubtedly be more noisy than that.
The result is that determining which team has the best home-court advantage is impossible with any degree of certainty. Even distinguishing between the tenth-best and 60th-best home-court advantage is on shaky ground. It’s probably best to think of of home-court rankings in groups of three. Teams rated in the top-third probably have an above-average home-court advantage and teams in bottom-third probably have a below average home-court advantage.
Nonetheless, I have posted a team’s home-court advantage computed from this method at the bottom of each team’s schedule. In light of the previous paragraph, the rankings and values are mostly for conversational fodder at your next cocktail party.
Along those lines, the team that currently owns the top ranking in home-court advantage is Air Force, at 4.5 points. An unlikely choice to be sure, and it’s worth repeating that we can never know which team has the best home-court advantage. It is probably not Air Force, a team that plays in a dingy 5,800 seat arena that requires clearing a security checkpoint to get to.
However, it’s illustrative of the fact that home-court advantage and team quality do not have to be related. The Falcons own the second-longest active losing streak in road conference games at 22. And over that time they’ve gone 13-10 in conference games at home. It’s a safe bet they benefit from an above-average home-court advantage."