Thursday, March 13, 2014

The REAL True Shooting Percentage

So there's this stat that ESPN NBA analysts use all the time called true shooting percentage. It is intended to measure a player's shooting ability more accurately, as it accounts for free throws and three-pointers. However, when I saw the equation used to calculate it, I didn't understand how it accomplished its goal at all. Here's the equation:

True Shooting Percentage = Total points / [(FGA + (0.44 x FTA)]


In my research, I learned that the equation was created to account for the number of possessions a shot consumes. This helps explain the (.44 x FTA) part of the equation, as usually, the other team gets the ball after a pair of free throws, and some free throws come after a made shot on a three-point play, so such a free throw is a chance for points that doesn't even take up a possession. 0.44 was reasonable because it was slightly less than one-half, or .5, and therefore accounted for the possessions a free throw consumes fairly well. 

However, this means that "True Shooting Percentage" is a misleading name for this statistic; it is more a measure of efficiency per possession than per shot. So, I made my own, more reasonable True Shooting Percentage equation:

Laski True Shooting Percentage = Total Points / [FTA + (2 x FGA) + 3PA]

Or, more simply: LTS% = Points Scored / Total Possible Points 

This equation encompasses all types of shots accurately, as each three-point shot is worth three points,each regular field goal is worth two, and each free throw is worth one. The resulting percentage represents the percentage of points a player scored out of the possible number of points they could have scored if they never missed a shot of any kind.

Stephen Curry's Laski True Shooting Percentage so far this season:

1459/[276 + (2 x 1108) + 492] = 0.4889 --> 48.9%

Works Cited:

http://theoldnorthking.blogspot.com/2013/01/true-shooting-percentage.html

http://espn.go.com/nba/statistics/player/_/stat/scoring

1 comment:

  1. Wow it is very impressive that you were able to create your own equation Joe. They should definitely use this into account.

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