# NBA Home Court Advantage Analysis

By | January 24, 2017

Author: Ting Lei

# 1. Introduction

Every sports fan knows that their favorite teams have more chance to win on the home court; and for professional athletes, they will surely make every effort to secure home-court victories in the regular season. The goal of this article is to 1) determine which teams in the NBA have the best home-court advantage; 2) provide some insights into how does the number of rest days of home and away teams impact the home-court advantage; as well as 3) determine what are some other possible factors to home-court advantage from 2011-2012 through 2015-2016 seasons.

Why do we choose NBA among the four major American pro sports?

• NBA shows the biggest home-court advantage of the four major American pro sports, with a historically overall winning percentage at nearly 60%.
• Two remarkable history made in 2015-2016 NBA regular season: The San Antonio Spurs have tied the all-time record for most home wins in a regular season 41-1, and the Golden State Warriors have won 54 consecutive games at home from January 31st of 2015 to March 29, 2016.
• NBA features matchups on daily basis where one team has a rest advantage over the other, which provides benefit for us to determine to what extent rest-disproportional schedule has an impact on home-court advantage.

# 2. Analysis

## 2.1 Software Used

We used Excel to process our dataset with preliminary data cleaning and integration. Tableau is also used for data analysis and visualization.

## 2.2 Dataset

The dataset is retrieved from the basketball-reference website: http://www.basketball-reference.com/leagues/. It provides game logs which contains home/away team name, date, score, stats, number of attendance, and number of foul calls from 2011-2012 through 2015-2016 seasons. The rest-days data are not provided for each game log, so we used Excel to manually calculate the days of rest prior to each game for the home/away teams to find the impact of rest on home-court advantage.

## 2.3 Approaches

In order to quantitatively define the home court advantage, we designed two indicators to represent how much better each team performs at home than away. Indicator 1 denotes the difference of winning percentage between home and away games for each team in Figure 1, and Indicator 2 denotes the average scoring margin between home and away games for each team in Figure 2 above. Based on the two indicators, we were able to identify the top home-court advantage NBA teams, which are the Portland Trail Blazers, Utah Jazz, and Oklahoma City Thunder.

Figure 1: Home Court Advantage Indicator 1. Color shows Percentage Win Margin as an attribute.

Figure 2: Home Court Advantage Indicator 2. Color Shows Home/Away game Margin as an attribute.

With the data of rest-days we calculated in Excel, we could also explore the relationship between the rest days and home-court advantage. Table 1 below shows the number of data tuples (number of games) according to different number of rest days for home teams and away teams. We could see that not only the away teams are much more likely to play back-to-back games, they are also more likely to be placed in matchups where home teams have a rest advantage over them.

Table 1: Distribution of Rest for Home vs. Away Teams

In Table 1, we discovered that some certain categories of rest day distribution had less than 100 tuples. Since smaller dataset would be more likely to lead to biased results, we decided to omit these data in our analysis presented in Table 2, which shows the relation between different rest days for home/away teams and average winning margin.

Table 2: Average Margin of Victory Points for home teams based on distribution of rest for Home vs Away Teams

In general, we found that the more days of rest home team gets, the higher the margin of victory point the home team will get; conversely, the more days of rest for away team, the lower the margin of victory point the home team will get.

Based on Table 2, we could also see that under same rest conditions, home teams maintained an average of 2.757 victory points, which is calculated based on the average point margin per game when home team and away team have the same number of rest days. However, the average home court advantage of all games shows 2.800 victory points, which is slightly higher because home teams are less likely to be placed in matchups with less rest days than away teams.

Then we try to identify if there are other possible factors that could impact the home-court advantage in the NBA.

• Time

In the Figure 3 below, the x-axis represents the months in a season and y-axis represents the average of the home win margin per game from the past five season. The result indicates that teams have the lowest home court winning margin in February. We believed that it can be explained by the All-Star Weekend held every year in that month, during which every team will take a long period of break. Such results related to over-resting are also seen in Table 2 above: when both teams have more than 3 days of rest, the winning margin of home teams reduce significantly. Overall, we could conclude that home court advantage will be diminished if both teams are in well-rested situations.

Figure 3: Average point margin per game vs. month

• Geographic Location

In figure 4 below, we show the geographic location of each team on the map with different shapes representing different divisions in the league. The home-court advantage index is represented by different color. With the color closer to red, the team has a better home-court advantage. Figure 4 clearly shows that the Northwest division have the most home-court advantage. We believed that the altitudes of the arena locations may be a possible factor, as Salt Lake City and Denver both located in one of the highest elevation states among United States.

Figure 4: Geographic location of each NBA team

• Referee Bias

Figure 5 below shows how the referee bias contributes to the home-court advantage. We used the blue line to indicate the home-court advantage index, and red line to indicate the average foul calls margin per game between each team and their visiting opponents. We can see that the team with a better home-court advantages are the ones with lesser foul calls than visiting teams during the game.

Figure 5: Home Court Advantage vs. Average Foul Calls Margin per game

• Crowd Support

Figure 6 below shows the relationship of the supportive crowd and the home-court advantage. Again the blue line represents the home-court advantage index, and the red line represents the average home game attendance for each team. In the figure, we found that lower attendance tend to result in a lower index. However, there are some exceptions such as LA Lakers, Chicago Bulls, and NY Knick. We believe this can be explained by the fact that those teams are the most popular team in NBA and they attract large amount of attendance no matter how they perform on home court (highlight in red rectangle). Another thing worth to be noticed is the average attendance for San Antonio Spurs and Oklahoma City Thunder, both teams have a relatively low average attendance because they have a small-size arena compare to other teams in the league (highlight in blue rectangle).

Figure 6: Average Attendance vs. Home Court Advantage

# 3. Results and Conclusion

In this article, we demonstrate the use of Tableau to run data visualization regarding to the home-court advantage in NBA from 2011-2012 through 2015-2016 seasons. Considering the results obtained based on our Indicator 1 & 2, we were able to summarize the top teams with the most home-court advantage as listed in the table below.

 Ranking NBA Team Name 1 Portland Trail Blazer 2 Utah Jazz 3 Oklahoma City Thunder 4 San Antonio Spurs 5 Indiana Pacers 6 Houston Rockets

In terms of the influence of rest days on home court advantage, we concluded that the more days of rest home team gets, and the less days of rest visitor team gets, the larger home win probability there will be. We could also see that with same number of rest days, home teams would defeat the visitor by 2.757 points, which is less than the average home win margin of 2.800.  It is due to that home teams are less likely to be placed in matchups with less rest days than away teams.

Last but not least, we also explored the relation between home-court advantage and other factors such as time of the year, geographic location, average foul calls margin, as well as the average attendance. In general, our results show that: in February home teams get least home advantage; large home court advantages at North West Division could be explained by altitude; visitor teams get more fouls than they do at home; attendance and home court advantage has a positive relation except for some arenas that are too popular or too small.

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## 33 thoughts on “NBA Home Court Advantage Analysis”

1. wenhao

interesting topic. I believe it would be better if you use attendance rate (attendance/full stadium capacity) instead of attendance. The home court advantage is correlated with attendance but we cannot say the higher the attendance the more home advantage. Team has high attendance probably because they have decent performance.

2. Zihao Li

I really like this topic, and surprised by the results shown here… which Portland has the biggest advantage for the differences between winning at home versus away. You said u use the data for both 2011-2016, which I found to be more variation with the data due to the changeover of the entire league, like most of the talented players are traded to the same team, and therefore that might cause more people come to the home court to support, like Golden States Warriors, which I thought would be the top list.. But I do like the overall analysis you gave in this paper by considering various factors that might influence the results, like the geographic locations.

3. Michael Baer

This was a very nice analysis of a very well-known concept. The one thing I’m particularly interested in is how the binary win-loss data was combined with the point-marginal data to determine the overall best home-court advantages. I also think its very interesting how the percent margins were positively correlated with attendance and negatively correlated with fouls called.

4. Lizzy Svigelj

This is very interesting, thank you for sharing! I wonder how this compares to other professional sports. Another interesting factor to look at would be weather, especially for outdoor sports like Football and Baseball. Do you have any predictions or thoughts on how weather might influence a home-field advantage?

5. Jesse Parritz

Very interesting analysis! I’d be curious to further explore the differences between the teams that have widely varying home court advantage metrics. Specifically, I’d want to understand if there are measurable differences in the cities like demographic data that might drive stronger vs weaker home court advantage. One of these factors might be what percentage of citizens attend home games and/or consider themselves strong supporters of their home teams. It’d be interesting to see how geographic metrics influence this as well (for example, smaller states with one concentrated mass of people vs larger states with people spread farther away from each other). Perhaps knowing these results could help the teams further improve their home court advantage 🙂

1. David Sweetapple

This is a very interesting and well done analysis. I like how you included rest days and referee bias in the analysis as these are important, yet often overlooked contributing factors. Another way to possibly eliminate outlying data points would be to limit your analysis to only the games each team has played before clinching playoff birth. Often times, once a team clinches the playoff birth it begins to rest its starting players and fail to put forth the same level of effort. This could skew the data in the sense that a home-court dominant team may lose more home games than usual during the last few games of the season.

6. Collin Peters

I really like this topic. I am a big NBA fan and was very interested in your analysis. One thing that I thought was particularly interesting was that the Chicago Bulls were found to be the lowest in terms of home court advantage. This is very interesting because they also have had the highest attendance of fans over that same time period.

7. Thomas Magnuson

Thank you, Ting, for sharing your interesting findings. I enjoyed reading about the lesser-thought about topics such as days rest and fouls called. I am curious if teams have any flexibility in scheduling to allow their teams to spread out their games against more competitive opponents, allowing them more rest beforehand. I am also curious as to how travel time also affects a team’s ability to feel prepared for games. For example, if the home team had to travel a long distance vs. a short distance to their next game.

8. Henry Rose

Being a huge sports fan I really appreciate the fact that you did this analysis. I’ve always wonder whether you can quantify home court advantage and that seems to be what you were able to do here. To extend this analysis into the playoffs, I think that it would be cool to look at how the 2-2-1-1-1 playoff format affects the outcome of a playoff series. A 2-3-2 allows for the same number of games to be played home and away, but allows for a team to play more consecutive games at home. Would that change the momentum of a series as opposed to a 2-2-1-1-1? Great article.

9. Eric Fleming

This was very interesting. One further bit of analysis I would love to see is if newer arenas tend to have better home court advantages. An improvement to team performance is often one of the promises used to justify massive expenditures on updated, modern stadiums and arenas. I’d also be curious to see if the promised improved fan experience of newer arenas translates into higher crowd support. I think this arena-age analysis would be an interesting comment on whether experts in arena design have home court advantage figured out. If they can design newer arenas that lead to a bigger home field advantage, then that should show in the analysis.

10. Ben Pollak

This was a very cool article to read as an avid NBA fan. In particular, it was interesting to see that geography/division plays a part in home court advantage, as I had never thought of that as a possibility. For the referee bias analysis, I wonder whether it’s really fair to call it a bias if some teams just play more aggressively than other teams. Also, for the home crowd support analysis, I’m not sure it’s a mutually exclusive relationship. While it is true that the home crowd support can play a part in the outcome of the game, it is also true that the strength of a team plays a part in the crowd attendance, particularly for low-market teams. It would be interesting to look at the low market team attendances during winning seasons vs during losing seasons and see if the results are the same. Again, very interesting to read.

11. Maxsen Berken

It would be interesting to see how different sports within a city effects the performance of basketball teams. Minnesota is much more interested in Hockey, so it would make intuitive sense that on days where the Wild play, the Timberwolves would not perform as well. City size would also be interesting to see. In cities where there are more things to do, maybe their home field advantage would not be as strong? The project was performed well and explained well in this post. Great work!

12. Erik Pechnick

Very interesting to read. I was wondering how often home teams actually receive three days rest with an away team coming to town. Most teams rarely even get two days rest, so i cant imagine that a team with three days rest at home would play a no rest team on the road very often. But it does make sense that the home team would win that game most if not all the time

13. Recordo Thomas

Very good and detailed analysis. I like how you highlighted what team has had the team that has the highest home court advantage over the period. It makes sense however that a team will more likely to win if they have more time to rest and “get their legs back” as termed in the world of sports.

14. Shelby

Really interesting analysis. I liked how you showed how geographical region could have an influence. I found it interesting that the Northwest division has the most home-court advantage. I had never thought about location being a factor before but it makes sense that where a team comes from makes a difference because it also dictates their fanbase.

15. Alejandro

It was a really interesting topic. It would also be interesting to apply it to soccer in Europe where teams from different countries and cultures are playing together. I’m a big soccer fan and it is really surprising how the best teams percentage of wins is decreasing when they play in countries as Rusia, where the weather is much colder than the average in Europe, or Turkey, where the supporters are known as the most violents of the continent.

Wheather is not applicable to basketball since it is played outdors but it would be interesting to analize the supporters background and culture from the teams with the highest home come success.

16. David Wilkins

As a huge sports fan myself, I found this analysis very interesting. Your ability to quantify home court advantage, and take several potential factors into account such as geographical location, attendance, fouls called, etc. made for a very robust analysis. I would like to see the attendance analysis expanded a little bit. I’ll use the MLB for a good analogy: everyone from Chicago that’s a Cubs fan likes to talk about how many of their fans fill Miller Park when they play the Brewers. So even though attendance in Milwaukee is high, they often claim that they still have home field advantage. I think this concept could be applied to certain games within this analysis.

17. Tom Dreher

This analysis of home court advantage, and how it varies from team to team, is something I have never seen investigated in the NBA before. I thought the authors did an excellent job of combining different types of data to find information and insights that would be not normally be very obvious. One thing that I think could have been done better was the display of results and explanation of figures/graphs. I know a lot of these findings were significant, but the way they were presented was sometimes a bit confusing. Overall, good work and well done!

18. J Weigandt

Super topic for analysis. I was quite surprised to see that the advantage fades if both teams have 3 days of rest. It would also be interesting to evaluate the point margins midway and 3/4 in the game to potentially observe a performance decline with respect to the teams’ rest. Thank you for posting. If there not already, the NBA could be crunching these numbers for more buzzer-beating, nail-biting finishes.

19. Alec Bernstein

I really enjoyed reading this analysis! You always hear of home field advantage affecting the likes of Quarterbacks trying to receive and call plays in the NFL, but to see how it affects the NBA game was very interesting. Figure 4 provided some really nice insight on home field advantage by geographic location. I always think of high altitude affecting various sporting events held outdoors, but to see the affect on NBA games was a fascinating take.

This is really interesting, especially given that results of studies on the efficacy of high altitude training are so mixed. However, I’d wager that, in the short term (i.e. a team from Miami flying into Denver), the advantage that the home team has due to the altitude is noticeable, as the players from Miami aren’t used to the change in performance brought about by the thinner atmosphere.

I think a really interesting longer term study would be to compare an individual player’s performance in athletic measures (running, jumping, etc) when they are traded from:

– a team at or near sea level to a team at high altitude, OR
– a team at high altitude to a team at or near sea level

This might give a better understanding of the impact of high altitude training over extended periods of time on elite athletes performing the same tasks in subsequent years.

20. MacKenzie Lundstrom

“In general, we found that the more days of rest home team gets, the higher the margin of victory point the home team will get; conversely, the more days of rest for away team, the lower the margin of victory point the home team will get.” This makes a lot of sense!

21. Trevor

This topic quickly caught my attention being an NBA fan and basketball fanatic. First off, I was surprised to see that the Northwest has the greatest home court advantage amongst NBA teams. It makes sense that the higher elevation of this region would make it more challenging for away teams to perform well, but my main focus on home court advantage was in relation to the crowd and fan base. The Northwest does not have big market teams like the Lakers, Celtics or Bulls. I would have predicted that big market teams perform better at home because they have more fans at each game on average. Additionally, big market teams are typically in big cities. When road teams visit big cities, I would think there are more off court distractions with the media, sight-seeing and nightlife that would contribute to an increased advantage for those home teams. However, this particular analysis does not support my intuitions. Overall, this work provides comprehensive analysis of NBA home court advantage and I think that the number of rest days is a very significant factor.

22. Carter Emerson

I liked how rest days were considered when accounting for home court advantage. NBA teams play a lot of games during the season and usually only have a day or two of rest. An interesting stat to look at would be how they perform on their third, fourth, or fifth game of a particular road trip. This might correlate to poor sleep and poor performance from players. Thanks for sharing.

23. Benny Boelter

It would be interesting to see how the data would change if the same analysis was done for this 2019-2020 NBA season. With the “superteam” era now pretty much over, most teams have all-star duos instead of an all-star starting five. I think that it would be interesting to see overtime what franchises home-court advantage has improved or dwindled.

Interesting project! I found it fascinating that you decided to look at geographic locations and its correlation with most home-court advantages. I agree with your analysis that a possible reason that Northwest division have the most home-court advantages is due to high elevations in the areas. I also thought it was really interesting to see the correlation between a supportive crowd and the home-court advantage, and it seems intuitive that you found that lower attendance tend to result in a lower index other than really popular teams like Chicago Bulls. Overall, great visuals and analysis!

25. Koryn Kessler

As a huge fan of the NBA I found this article very interesting. I wonder how this correlates to other sports with different factors to consider such as weather. I thought some of the graphs were hard to read quickly and needed deeper analysis to comprehend.

26. Saksham Garg

It would be interesting to see how this data would change for the subsequent seasons, especially after the fall of the dubs.

27. Joseph Dunleavy

My hometown team, the Chicago Bulls, ranked as the team with the lowest rating of home-court advantage. This is super surprising given that they also had the highest attendance. This may be because the Bulls have not been very good in recent times, and Chicago is a huge metropolitan area.

28. Richard Berry

As an NBA fan, I know how big of a deal a home-court advantage can be. I was happy to see a section about the refs and if there was a bias towards the home team. When first analyzing Figure 1, I was surprised the Northwest had the biggest home-court advantage. Figure 4 does a great job of elaborating why the Northwest division has this advantage. When NBA teams travel, they usually have multiple road games in a row. Something interesting to add would be to look at how teams perform throughout their trip and if their performance decreases. Lastly, in the finals it seems like every team wins when at home. It would be interesting to take a closer look at just the finals or playoffs and then analyze home-court advantage.

29. Michael Fuchs

As an NBA fan, I thought that the data would support the idea of home-court advantage. I know in Milwaukee it gets rowdy and definitely plays a factor in the game. I was surprised though that the data didn’t reflect it as much. It makes sense the period of rest had a large impact on performance though.

30. Srikar Vootkur

Thank you for your analysis on home-court advantage in the NBA! I have always been curious what causes the disparity in home and away for basically every team. What really surprised me was that every single team in your results had more home court wins, with the lowest % margin being 0.1269! This means that there is definitely a difference based on how plentiful your data is (a t-test could be done to prove this for a very high certainty). I would like to see other studies analyze how much altitude affects performance, since this is quite an unfair advantage for teams like Denver.

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