NBA basketball is the one the sports I enjoy watching the most. As I was ordering my (undisclosed amount)th beer while watching a game during after-work hours, it occurred to me how often I had seen sparsely populated arenas during games, with large areas of seats going unoccupied. This got me to thinking about the average fan attendance for NBA teams, what could be the factors influencing attendance, and ultimately, which NBA team had the most loyal fans?
After some online browsing, Python scraping and data cleansing, I was able to obtain a good amount of data from the awesome guys at basketball-reference.com. Unfortunately, I could not find any records of fan attendance beyond 1981, so this analysis will be restricted to the period between 1981 to 2013 (with records for 2002-2006 also missing). First, I wanted to see if there were any trends in NBA fan attendance per season.
Fan attendance for each NBA teams during the seasons 1981 to 2013. Years marked with a red asterik represent shortened seasons due to a lockout. Data for the year 2002 to 2006 was not available
The two most striking features of the plot above are the obvious increase in fan attendance from 1981 to 1995, and the subsequent stagnation thereafter. This makes sense, since this period is widely regarded as the golden era and renaissance of basketball, full of rivalries and Hall of Fame players in their prime. Unsurprisingly, the year 1999 and 2012, which were both shortened by ~4 months due to a lockout, saw a drop in total number of fan attendance (purely as a result of lesser games being played – if I were more rigorous, I would normalize for this and also the overall US population, but I wanted to visualize the raw numbers).
Next, I investigated whether team success (the net number of wins per season) during a season could be an indicator of fan attendance. Not surprisingly, teams that won more also attracted more fans (doh!). This was true regardless of the conference in which the team was (East or West).
Fan attendance as a function of number of wins for all NBA teams during the period of 1981-2013
I also looked at whether fans were more attracted by teams that scored a lot, or by teams that put an emphasis on defense. However, I had to consider historical trends in scoring, and adjust for the fact that defenses/offenses have gotten more sophisticated over time. Therefore, I decided to look at the fan attendance numbers of each NBA team during a given season, and plot that as a function team’s deviation from the median number of points scored by all teams during that season. The plot below shows the aggregate of all points after considering each individual season between 1981 and 2013. Interestingly, although teams that score more attract more fans, it seems that good defense is even more likely to attract crowds.
Fan attendance as a function of the number of points scored for and against the home team. To adjust for the variability in offensive/defensive points scored at each season, the attendance numbers are plotted against the home team’s deviation from the season average.
Of course, the caveat of the above plot is that teams that score a lot and/or defend well are more likely to win, and thus attract more fans. Indeed, winning teams usually develop bandwagon fans and thus inflate their attendance numbers. Therefore, I sought to find out who were the most loyal fans in the NBA. In my mind, the mark of a truly loyal fanbase is one that shows up to support its team regardless of win/loss ratio. For these reasons, I plotted the fan attendance of each NBA team normalized per number of wins.
And so the most loyal fanbase are the good people of Memphis, Minnesota and Toronto!
I will add all the relevant code to my github account soon (basically as soon as I’ve commented it!)
Stat Of Mind 
Very neat! Looking forward to seeing the code. Cool style too!
I think the bottom end of your ranking is more interesting. Do Boston, LAL, and San Antonio rank badly because they have been consistently good for so long (thus there aren’t many bad seasons for attendance to drop) or because the fans are really just fair-weather fans on a good run.
This is some great stuff. A few things came to my mind: issues of stadium capacity (as well as teams changing stadiums), the number of professional teams a city has, and the price of tickets. I know when the Celtics started to suck and consistently lose, prices were still really high. I imagine %Capacity would be a better measure for attendance but then you still have to deal with the issue of businesses buying up tickets (in some cases to avoid local blackouts). Wonder how it would change if you took into consideration sellouts or maybe 90%+ capacity.
Great comments. To answer your questions (or rather suggestions), I did consider arena capacity but never got around to accounting for it. In hindsight, that was a bad decision, which I based on the fact that the most arenas had (in my eyes) very similar capacities ranging from ~18,000 to ~21,000.
The number of professional teams and tickets prices is a great idea (hadn’t considered that!). Likewise, I would be curious to see how local weather or entertainment (such as other pro teams) influence attendance. I also completely agree on the concept of %capacity…that was my original intention but I couldn’t find the appropriate data. Furthermore, there are still issues such as “tickets sold” vs. “number of people who show up”, and it has never been clear to me which one counts as “attendance”. Thanks for your comments!
To add to this, there are a number of other factors to consider:
– teams relocating (Seattle to OKC, NJ to Brooklyn etc…)
– expansion teams (they will see an inflation of attendance during the first year)
– teams changing stadium (like you said)
I completely agree. I was actually considering looking at things such as weather, or the amount of entertainment available in each city. I would be curious to find out to what degree much this would affect people’s decision to attend a game or not.
This makes no sense. You need to standardize the data. Portland’s Rose Garden only holds 19k people. Portland had the longest home sell out streak in NBA history: 1977 through 1995, the team sold out 814 consecutive home games, the longest such streak in American major professional sports.
Thanks for your comment. The arena capacity is a good point, and one I had considered, but the tight variance of NBA arena capacities made me overlook that. In hindsight, it is something I would adjust for, although it is not obvious to me that it would necessary have any kind of impact. With regards to the Portland streak, the data that was analyzed was from 1981 to 2013, so from 1995 when the streak ended, that’s at least 18 years during which a lot happened to the Blazers!
Just FYI, you should be able to find a LOT more NBA attendance data at Rodney Fort’s Sports Business Data website, including missing years in the 2000s and going all the way back through the merger and the 50s for teams like the Knicks.
Awesome! Thanks a lot for letting me know, it looks like a great resource for data. I have to admit I’d never come across it before! Thanks again! I may actually edit my original post in order to incorporate this data!
This maybe a stupid question but how did you normalize for number of wins? Did you pick take data from a few winning seasons and few losing seasons from each team, average it, and plot it?