Joe reviews some Box Plus-Minus numbers and shares a couple scatterplots!
Plus-Minus
Over the course of the year I'd noticed some chatter in the comments about plus-minus data and I thought it'd be interesting to revisit the topic again, this time for the 2014-15 season.
About a year ago, I wrote a primer on Adjusted Statistical Plus-Minus and gave some caveats for this analysis. It's important to note: adjusted statistical plus-minus (ASPM) and box plus-minus (BPM) are the same things. The bullet points:
- Plus-minus is the Holy Grail of stats, because it captures everything
- Because plus-minus catches everything, the data is noisy
- So noisy, in fact, that viewing raw plus-minus doesn't say much
- In the NBA, it is possible to do regression analyses on raw plus-minus data, eliminating noise
- In the NCAA, there are too many teams and too few games to regress upon
- We can use an equation to guess what a player's regressed plus-minus score is, based upon box score stats
As you might expect, using only box score stats to predict players' value does yield some unexpected results.