It’s the fourth quarter and there are only a few minutes left in the game. Everyone in the stadium is on the edge of their seat, hoping that their team will be able to come out with the win. The home team has the crowd cheering them on, roaring when they make a shot and booing when the opponent makes one. The familiarity of the basketball court helps the home team feel comfortable, while the away team is uncomfortable with the different court feel and the crowd going against them. The away team is also dealing with the difficulty of having to travel before the game, causing the players and coaches to feel a little bit more tired than usual, affecting their play slightly enough to make one costly mistake that can lose them the game.
All of these factors combined are the reasons that home court advantage is such an important thing in basketball. They are the reason that NBA teams play for the number one seed during the regular season. But how much of an advantage does having home court give? Is NBA home court advantage better than other sports? And which teams and players are most positively affected while playing at home? And is home court advantage stronger in the college level of basketball? There are so many questions about home court advantage that can be answered with a look into the data of basketball games for the home teams compared to the road teams.
The first question that I will attempt to answer is which major sports league has the best home advantage. Is it the NBA, NFL, MLB, and NHL? To do this, I looked at regular season and playoff win percentages of the last five years for each of the leagues. The results are displayed below.
The numbers in the graph represent home win percentage above average. This basically summarizes how much greater the winning percentage is for the home team than the average winning percentage. The stat was calculated by taking the home winning percentage and subtracting 0.5 (because that is the average winning percentage of all teams). As you can see by the graph, the NBA has the largest regular season home advantage, about 2 percentage points greater than the NFL. Additionally, the NBA had the second best post season win percentage, only 1.8 percentage points fewer than the NFL. In summary, the NBA has a better home advantage than the NHL and MLB, but a comparable home advantage to the NFL.
How the Home Team Gets the Advantage
The next question that I want to answer is how the home team wins more often than the road team. In order to distinguish what gives the home team the advantage in the actual game, I looked into which stats were most affected by home advantage. Theoretically, the home team and away team should have the same average values of each stat category given that there is no home advantage. Using this, I conducted statistical tests to find which stats had the greatest difference between the home team’s value and the road team’s value.
The chart shows which stats had the greatest statistical difference between the home and road team. The second column represents the test’s p-value, which can be interpreted as the probability of the results happening by random chance given that there is no home court advantage. A lower p-value means that there is more statistical evidence that the home team is better than the away team at that particular aspect of the game. Since the majority of the stats had a very low p-value (under 0.05 is usually regarded as statistically significant), there is an obvious home court advantage. The stats that the home team improves on at home are assists, scoring, offensive rebounding, and shooting. On the contrary, FT% and TOV% are not significantly affected by home court advantage. Additionally, the p-values give evidence that NBA scorekeepers have bias towards the home team when recording assists (AST p-value) and that referees have a slight bias towards the home team when calling fouls (PF p-value).
Which NBA Teams are Most Affected by Home Court
Having home court is an advantage for all of the teams in the NBA, but some teams have a greater home court advantage than others. The teams with better home court advantages have a larger margin of victory at home than on the road. Teams with a good home court advantage can either be really good at home but average on the road, or they can be really bad on the road and average at home. After going through the home and road splits for each NBA team for the last five years, I found which teams have had the best home court advantage in recent years.
As seen by the chart (and the image above), the 76ers have had the best home court advantage of the last five years. One of the reasons the 76ers are at the top of the home vs road margin of victory difference is because of their home and road performances this season. The 76ers are 29-2 in Philly this year with a margin of victory of 10.4. Meanwhile, they are 10-24 on the road, a record similar to that of the Knicks, with a margin of victory of -5.2. They are followed by the Trail Blazers, Nuggets, Pistons, and Spurs as the teams with the best home advantage. The teams with the worst home court advantages were the Kings, Pelicans, and Bulls.
Which Players are Most Affected by Home Court
While the effect of home court advantage is obvious for NBA teams, it is not as obvious for the players. Many players do not play obviously better at home versus the road. However, since teams are affected by home court, players also have to be. I wanted to see which all stars from the past two years have had the most difference between their home and road performances during their careers.
I first started to try to see the difference between home and road performance by using the splits of stats such as points per game, assists per game, true shooting percentage, and free throw percentage. Then, I realized that I wasn’t incorporating an entire half of the game, defense. Therefore, I instead used the all stars’ offensive and defensive rating differences to discover which players are most affected by home court. The most affected players were Joel Embiid (which makes sense because the 76ers have the best home advantage), Kemba Walker, and Nikola Jokic. The least affected players were Jayson Tatum (the only player who actually performed better on the road), Devin Booker, Karl Anthony Towns, and Victor Oladipo.
NBA Home Court Advantage through the Years
The advantage of having home court in the NBA does not stay steady throughout every year. Some seasons have a greater home team winning percentage than others due to both random chance and the changing value of being the home team. I recorded the home team winning percentages for every season since the 1996-97 season to determine if NBA home court advantage has changed or not. The results were that the home team winning percentage was often in the range of 57% to 65%. However, one interesting finding was that this years home winning percentage was just about 55%, lower than previous years. It could just be an anomaly or a new trend, as the home winning percentage seems to be slowly decreasing. Additionally, I recorded the playoffs home advantage. Those results varied much more as the sample size was much smaller than that of the regular season. The home winning percentage in the playoffs was often between 55% and 75%. A larger home winning percentage should be expected in the playoffs as the team with the better record is the team that is at home most often.
Home court advantage is present in all levels of basketball, not just the NBA. But which level of basketball does having home court have the largest impact, college or professional? By looking into the home winning percentage and margin of victory difference of NCAA basketball major conference teams, the college basketball conferences with the best home court advantage can be found and a comparison between college home court and NBA home court can be made.
The results of win% above average and margin of victory difference give several insights into home advantage in college basketball. Since the sample of the data was only taken from the results of this year, the results can only be generalized to the 2019-20 college basketball season. Moreover, the sample only included conference games so games that the home team played a far inferior opponent were not counted. This college basketball season, the Pac 12, Big 12, and Big Ten had the best home advantages. Home teams in the Pac 12 won over 70% of the time, and home teams in the Big 12 did about 6 points better on average than they did on the road. Additionally, the graph presents evidence that college basketball home advantage is more important than the NBA as the NBA ranked below each conference and the NCAA power 5 teams as a whole in both win percentage above average and margin of victory difference.
Home court advantage in the NBA and college basketball is an important factor that contributes to team performances and player performances. The NBA has the best regular season home advantage among the four major US sports leagues, and therefore is crucial to the outcome of a game. Home court advantage influences stats such as assists, points, and offensive rebounding percentage, while also affecting how well the teams play. Teams such as the 76ers, Trail Blazers, and Nuggets have the best home court advantage, and players such as Joel Embiid, Kemba Walker, and Nikola Jokic perform much better at home than on the road. In college basketball, home court advantage is even more influential on the outcome of the game. The home winning percentage for college basketball power 5 teams in conference play was about 65% and the margin of victory difference was almost 5 points. Home court advantage in the basketball is an element of the game that has a force on the outcome of a game in many ways.