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Effective Field Goal Percentage and True Shooting Percentage

Learn how these advanced metrics can help your team.

Advanced Basketball Stats are just starting to take off in the NBA and College Basketball. Now, we’re in the process of bringing them to every level of amateur basketball. 

One of the first areas that the basketball community needed to address was an understanding of how efficient different players are at scoring. Field Goal Percentage was supposed to do this in one simple analytic. However, FG% doesn’t differentiate between 2pt attempts and 3pt attempts, nor does it take into account free throws. So FG% really only tells you about one of the three different ways to score in basketball. Effective Field Goal Percentage and True Shooting Percentage were made to fill that gap.

Effective Field Goal Percentage

The idea behind eFG% is that shooting percentages should reflect the basic fact that a three pointer is worth more than a two pointer (by one point, obviously). While this doesn’t seem like a groundbreaking revelation, FG% fails to account for this. Say two players both shot 4/10 from the floor, but one player hit a three and the other didn’t. Both have the same shooting percentage of .400. But wouldn’t you rather have 9 points on 10 shots than 8 points on 10 shots? Yes. eFG% tells you what the FG% of a player would be if you counted total points scored on shots made instead of simply shots made.

If it seems like eFG% was created by 3pt specialists to provide them with leverage in negotiating contracts, that’s because it was. No, really. A 3pt made is worth one more point than a 2pt made, which is reflected in the formula. The exact formula is:

eFG% = (.5 x 3PM + FG) / FGA

There are two big drawbacks to eFG%. The first is that it only sheds light on players who take and make a lot of three point shots. If you don’t take three point shots, then your eFG% and FG% will be identical. The second problem is that it doesn’t include free throws. Which brings us to…

True Shooting Percentage

Effective Field Goal Percentage was a step forward, but is still incomplete as it doesn’t include free throws. True Shooting Percentage is designed to be a comprehensive measure of how efficiently a player scores, regardless of the method. It takes eFG% and goes one step further, including free throws in the equation. 

There are two reasons to include free throws in any formula designed to measure scoring efficiency: 1) some players are better free throw shooters than others; and 2) some players (generally those that take a high percentage of shots near the basket) shoot more often than others. Both parts of this equation are equally important – it does a player no good if they shoot a ton of free throws but can’t make any, nor does it do them any good if they’re perfect from the stripe but rarely get there.

So TS% attempts to measure how many points a player scored, relative to the number of possessions they used (more accurately, it’s points per possession divided by two to look like FG%).  The formula is:

TS% = PTS / ((.44 x FTA + FGA) x 2)

Let’s look at two player lines to see the difference in these stats. Here is the shooting line for each player:

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And here are their advanced stats:

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Notice that Player A had a higher eFG%, but a lower TS% than Player B. This is because Player A actually had a better day shooting the ball (5/10 from the field instead of 4/9), but Player B was actually the more efficient scorer. Player A had 13 points on 12 used possessions, but Player B was more efficient with 15 points on the same number of possessions.

While eFG% can tell you who had the better shooting day from the floor, TS% is able to accurately tell you who was the more efficient scorer during the game. 

Note: The .44 in TS% is an attempt to correct for the fact that most free throws come in pairs, but not all free throws are the result of a possession. Specifically, it’s designed to account for and-1′s and technical free throws. This is generally quite accurate in the aggregate, but be aware that on a per-game basis it can be slightly off.

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James Harden is a regular near the top of the TS% leader boards.