A quick analysis into the effects of dunking on winning NBA games

Dunks are a big part of NBA games for some obvious reasons: they excite the crowd, are worth two points, and are made a very high rate. But do dunks affect games in an even more significant way? Perhaps they fuel a team’s momentum, sparking better defense and offense. In other words, how do dunks correlate with winning games?

The Dunk Score

Before I get to the exact impact of dunks, I want to see how the correlation between dunking and winning. For the dunking variable, I want to incorporate more information than just the raw number of dunks per game. The variable needs to factor in missed dunks, too. Missed dunks are worse than no dunk attempt at all because they provide negative momentum for a team. For this reason, my dunking variable subtracts dunks that are either missed or blocked:

• Dunk Score = Made Dunks - Missed Dunks (either by fault of offensive player or by defensive block)

Data for the dunking variable and the game outcome came from NBA.com. I looked at every game in the 2014-2015 regular season to get a sense of this correlation.

Looking at the Dunk Score vs the actual score, there is a slight correlation of 0.13 (Orange is home team and Blue is away team):

The team with the higher Dunk Score also has a higher probability of winning the game:

Even though these probabilities aren’t drastically different from 50/50, the Dunk Score alone provides some predictive power for game outcomes. Some of this predictive power is obvious: dunks are worth two points and scoring more raises your overall score and your chance of winning. Next, I’ll try to separate out these effects by normalizing for the two points created by dunking.

Isolating the Effect of Dunking

Now that we’ve established that better dunking performances is linked with higher winning percentages, we can determine if dunks are worth anything more than two points. To achieve, this I went through the same set of 2014-2015 regular season games and normalized the scores for dunks. Each team’s score was calculated as this:

Adjusted Team Score = Team Score - 2*Dunks Made

Here’s the plot of comparing the Adjusted Score vs the Dunk Score:

There’s a negative correlation of -0.13, which suggests that higher dunk scores correlate with lower non-dunking points. With this analysis, it appears that a dunk is not worth more than a regular basket.