The strokes gained method of shot analysis was pioneered by Mark Broadie. He has created an innovative was of analyzing the game of golf using millions of shots tracked at PGA Tour events. The basic premise of shots gained is to determine how many shots on average it take a Tour player to hole out from a certain distance and location and then compare it to your results.
The simplest form of strokes gained is illustrated in a putting scenario.
Let's say you are faced with an 8 foot putt. From 8 feet the average PGA Tour player makes roughly 50% of the time and 2 putts the other 50% of the time. This leads to an expected strokes to hole out of 1.5.
50% x 1
50% x 2
If you make your 8 footer, you have gained .5 shots vs the average Tour player. If you 2 putt then you lose .5 shots.
Now for a full shot example. We will use a tee shot.
Let's say you step up to the tee on a 406 yard Par 4. From 406 yards off of a tee, the average PGA Tour player will take 4 shots to hole out. Imagine you hit a great drive, long and down the middle of the fairway leaving you 125 yards to the pin. From 125 yards in the fairway the PGA Tour player will average 2.86 shots to hole out.
The math for calculating your strokes gained on that tee shot would be as follows.
Average strokes to hole out from starting location- 4
Average strokes to hole out from finishing position- 2.86
1(for the shot it took you to get from point A to point B)
That drive would have gained you .14 shots.
Make sense? Great now go test out the Calculator!