NBA winning percentages

During a Milwaukee Bucks broadcast on February 11, John McGlocklin mentioned something to the effect of "the first team to get to 100 points usually wins." Intuitively, this makes some sense. If you're the first team to a given score, you have the lead at that point. 100 points is usually a late-game score, and having the lead near the end of the game makes it more likely you are going to win.

I was curious as to whether the data backed this up. I collected play-by-play scoring data for the 2013-2014 season, and ran some analysis on it. First, the number of times the first team to X points won or lost:

point totals

That's a little hard to read in the higher-scoring (interesting) portion of the graph. Here's the winning percentages plotted as a function of score:

nba point total ratios

Some notes:

  • There were 1319 games played, including playoffs.
  • Teams win at a .932 clip for scoring 100 first. Not a bad rule of thumb!
  • On the other hand: at no point having the lead gives you a sub-.500 winning percentage. So you could also say "the first team to 1 point usually wins".
  • The worst is 1 or 2 points, yielding wins at .547. Even getting to 3 first improves your chances a bit, an extra percent and a half, all the way up to .562.
  • The highest point total 145. The Rockets beat Lakers on the road on April 8. The game didn't even go to overtime!
  • There is a curious bump in the ratio at 121. This is an artifact of not many teams scoring that many and still losing - only 3 to 5 losses in that range. Makes for a noisy signal.
  • No team scoring 128 or more lost.

The Bucks were first to 100 that night, and beat the Kings 111-103 :)

Thanks to basketball-reference.com for the play-by-play data.