The F5's NBA Referee Database
The unofficial source on NBA officials
Hello readers of The F5.
This week I’m sharing my NBA referee database with paying subscribers. I think it’s cool. If you don’t want to sign up for a subscription to The F5, but still want to support this newsletter, you can always buy me a coffee.
One of my pet analytics hobbies is tracking NBA referee behavior. I’ve always felt it was one of those gaps in the NBA data space that could be filled if someone just put in the time.
So that’s what I did.
I counted up every foul and violation made by every NBA referee in the regular season since the 2020-21 NBA season. It’s more than 60,000 Shooting Fouls, over 2,500 Kicked Ball Violations, and 206 Ejections.
It’s worth pointing out that my counts are at the individual referee level as opposed to the three-man crew level, which is what you’ll find on most other sites that try to track referee tendencies.
Even though I have the data going back five seasons, I’m partial to using a three-year window when looking at the data. A three-year window allows us to focus our attention on the more recent past while still providing samples that are big enough to help us pick out some interesting details.
For example, which referee has doled out the most Technical Fouls since 2023-23.
These are Baseball Savant style charts where the numbers inside the bubbles represent the referee’s percentile rank within the corresponding category. The numbers on the far right of the chart are the raw values, which in this version are the total calls. James Williams’ 92 technical fouls put him in the 100th percentile over the last three regular seasons.
But totals aren’t the only way we can look at this data. We can also measure referees’s actions on a per 100 basis to account for any differences in the number of possessions each referee has been on the court. That’s helpful in case some referees for whatever reason have been involved in more overtime games or more up tempo games than others.
After normalizing the data we can see that even though James Williams has called the most technicals over the last three seasons, Brent Haskill leads the league in technicals per 100 possessions. In fairness, Haskill has less than 2,000 possessions under his belt over the last three seasons whereas Williams has more than 16,0000. Like most things in the NBA, you’ll want to take the totals and the rate-based stats into account if you’re trying to glean anything from the data.
I’ll have a lot more to say about referee data in the coming weeks, but I wanted to go ahead and share the three-year data in an interactive and searchable table with my paid subscribers. If you’re a free subscriber and want to know what the data looks like before subscribing I’ve embedded a sample clip below.
In addition to being able to access the referee database, paying subscribers to The F5 receive an extra email each week with more charts, analysis, and tutorials on how to recreate the visualizations you find in this newsletter using the R programming language.
The F5’s NBA Referee Database
If you’re reading this post in email, click on the table to open it in a web browser.