Strokes Gained-Putting: Questions and answers

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Answers to a few key questions about the PGA TOUR's newest statistic, Strokes Gained-Putting.

Why do we need a new putting statistic?

The current putting statistics each have inherent bias in them that either measure more than one aspect of the game or are open to be influenced by luck, and none take the distance of the putts into account. Here's an analysis of three key putting statistics and the bias with each one.

• Putts per Green in Regulation: This statistic computes the average number of putts for only those putts where the green is hit in regulation. The bias in this statistic is that it eliminates a large number of putting opportunities and favors a player who is more accurate with his approach shots.

• Putts per Round: This statistic computes the average number of putts taken per round. The bias in this statistic is that it rewards the player who misses greens, subsequently chips close to the hole and then one putts.

• Total Distance of Putts Made: This statistic computes the total distance per round of all putts made. The bias with this statistic is that it is influenced by a player making a very long putt (putts longer than 25 feet, for example). Putts of this length are as much a product of luck as they are of skill (less than 6 percent of putts are made from more than 25 feet).

What is the idea behind the new statistic?

The concept is to compute the difference between a player's performance on every green (the number of strokes it takes him to reach the hole) against the performance of the players he played against for a given round. This enables us to compute the number of strokes gained or lost due to putting on a round, event, and year-to-date basis.

This is very similar to the way scoring average takes into account the average scores of all players in the field.

How is the new statistic computed?

First, the average number of putts a TOUR player is expected to take is calculated from every distance, based on ShotLink data from the previous season. The actual number of putts taken by a player are subtracted from this average value to determine strokes gained or lost.

For example, the average number of putts used to hole out from 7 feet, 10 inches is 1.5. If a player one-putts from this distance, he gains 0.5 strokes (1.5 - 1). If he two-putts, he loses 0.5 strokes (1.5 - 2). If he three-putts, he loses 1.5 strokes (1.5 - 3).

For the final statistic, a player's strokes gained or lost putting is compared to the field. For example, if a player gained a total of three strokes over the course of a round and the field gained an average of one stroke, the player's "Strokes Gained Against the Field" would be two.

What have we learned from this exercise?

We can use the baseline to compute the probability of making putts at all distances: for example, a player has a 50 percent chance of making a putt from 7 feet, 10 inches.

When reviewing the baseline computed from 2004 through 2010, we see very little difference in the data, indicating that putting performance has remained relatively constant over that time.

When reviewing the results of the computed year-to-date statistics, we see definite differences between what has been previously computed by the other putting statistics.

Where do we go from here?

The TOUR is in the process of reviewing the results of the computations from 2004 through 2010 and has taken the step to ask a number of constituents to participate in this review. The goal is to gain feedback on the methodology being used, as well as the general feeling for the accuracy of the ranked lists being produced.

Once the feedback process is complete, the TOUR will review the results and will either make revisions to the computations or will begin to publish the new statistic and promote it as the primary statistic to be used in evaluating the best putters on TOUR.

Why is the statistic being called Strokes Gained-Putting?

The general thought is to compute additional statistics that would use a similar methodology to measure short game, approach shots and tee shots. Collectively this would yield Strokes Gained - Short Game; Strokes Gained - Approach Shots; Strokes Gained - Tee Shots (or something similar).