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Bringing Strokes Gained statistics to all golfers.

“Strokes Gained Per Round” vs. “Strokes Gained Per Stroke”

Strokes gained stats can be calculated and presented in two distinct ways: per stroke and per round.  Strokes Gained Golf generates both “Strokes Gained per round” and “Strokes Gained per stroke” statistics, because we strongly believe each offers unique advantages for measuring and tracking various golf skills.

“Strokes Gained per round” is the traditional way strokes gained stats have been calculated, and is the more common way of talking about strokes gained statistics.  The PGA Tour, for example, uses per round calculations to determine Strokes Gained Putting, Strokes Gained Tee to Green, and Total Strokes Gained.  It appears the Tour will continue to primarily use per round values as it develops more strokes gained stats such as Strokes Gained Driving.

“Strokes Gained per stroke” is a far less common way to generate strokes gained statistics, but offers its own unique analytical advantages.  In his book Every Shot Counts, Mark Broadie spends a paragraph describing the differences between the two approaches, but basically argues against the usefulness of per stroke measurements and focuses almost exclusively on per round numbers.

I will use this blog post to describe the advantages of each method.  In order to do so, we will examine a theoretical 18 hole round of golf played by Tom, a 10 handicap golfer.  Tom finished the round on September 8th, and dutifully entered the necessary data into the SGG Record-A-Round interface.  Tom scored a 78 on the par 72 course.

Of course, every shot that Tom took for the round has an associated strokes gained value. Some of those values are positive, indicating a shot that was better than the PGA Tour average.  Some of those values are negative, indicating a shot that was worse than the PGA Tour average.  In order to generate useful statistics from this raw strokes gained information, Strokes Gained Golf has created multiple “categories”, each representing a distance range and a defined skill:

  • Putting (all shots taken from the green)
  • 0-50 yds (all lies)
  • 51-100 yds (all lies)
  • 101-150 yds (all lies)
  • 151-200 yds (all lies)
  • 200+ yds (all lies minus par 4 and par 5 tee shots)
  • Driving (all Par 4 and Par 5 tee shots)
  • Total SG (all shots taken during the round)

Strokes Gained per round stats are calculated by adding up all SG values for all shots in a given category for a single round of golf.

Strokes Gained per stroke stats are calculated by averaging the SG values for all shots in a given category.

It really is that simple.

Going back to Tom, his statistics for the round show that he had a Total SG of -9.89 for the round.  In other words, a theoretical “Average PGA Pro” playing the same shots would have beat him by 9.89 strokes.  A further look at Tom’s SG Per Round for the round:

  • Total SG: -9.89
  • Putting: -0.25
  • 0-50: -3.11
  • 51-100: -0.31
  • 101-150: -1.88
  • 151-200: -1.50
  • 201+: -0.23
  • Driving: -2.61

These stats are very useful for seeing how Tom’s skill in each category affected his round as a whole.  For example, he lost only .25 strokes all day due to putting, but his 0-50 yard shots hurt him the most, costing him 3.11 strokes to the pro.  When viewing golf skill across categories, the per round stats are very helpful.  When looking at how his performance in every category affected his score, these stats are ideal.  Tom knows for this round which skills helped him and hurt him the most, giving him unprecedented guidance in understanding how the different parts of his game affect his score relative to each other. These per round stats are also very intuitive.  One quick look tells you exactly how many strokes were lost in each category.  The cumulative numbers for the round in each category are large enough to sink your teeth into – something the per stroke numbers do not offer.

One thing per round stats don’t tell you, however, is how many strokes were taken in each category.  So, while it is useful to know how many strokes Tom lost cumulatively to the pro in each category, Tom’s skill in each category is not precisely measured, because the number of shots taken in each category varies from round to round.

To illustrate the point, imagine a round in which Tom’s approach shots are consistently off, causing him to miss the greens more than usual and therefore increase his shots taken between 0-50 yards.  Because Tom in this case takes so many more shots than normal in this range, we would expect his Strokes Gained per round to be relatively poor for this round.  In other words, taking 20 shots instead of 10 for a golfer of Tom’s ability is likely to give him a cumulatively poorer result in this category.  The quality of each shot in the category, however, may have been average or even above average.

Consequently, Strokes Gained Golf realized early on that for accurately measuring and tracking a golfer’s skill in a given category, Strokes Gained per stroke is the best statistic.  Strokes Gained per round is still the best tool to measure many things, but is not the best tool for accurately measuring golfer skill.

Returning to Tom’s round, his Strokes Gained per stroke stats for the same round are as follows:

  • SG Total: -0.13
  • Putting: -0.01
  • 0-50 yds: -0.18
  • 51-100 yds: -0.31
  • 101-150 yds: -0.47
  • 151-200 yds: -0.30
  • 201+ yds: -0.12
  • Driving: -0.15

At first glance, these stats are not nearly as useful.  First of all, the numbers are so low that they are hard to understand.  On their own, these numbers don’t show us a whole lot. For example, I’m not sure intuitively how to judge “-0.31” strokes in the 51-100 category.  Is that good or bad?   However, if we are looking to understand our skill in a given category, these numbers are ideal.  Strokes Gained per stroke stats tell you precisely how you are performing on every shot.  They really become illuminating when they are tracked over time.  For example looking at SG per stroke stats in the 0-50 yard category round to round will tell you precisely how you are performing relative to other rounds played, accurately measuring every shot for it’s quality.

For Tom, the stats reflect the fact that he only took 3 shots for the entire round in the 201+ category.  The Per Round stats in that category are not measuring his skill accurately. Imagine that during his next round he takes 6 shots in that category.  This variation in shots per round can cause misleading per round results if they are not taken in context. Contrast the 201+ category with the Putting category, where Tom took 27 shots.  It is clear that each approach reveals unique, distinctly valuable information.

In the 0-50 yard category, Tom took a whopping 18 shots.  This is a perfect example of how per round stats can be somewhat misleading.  It appears this was his worst category for the round, losing him 3.11 strokes to the pro.  But a closer look reveals that because he took so many shots in the category, his skill at this range really wasn’t so bad after all.  The per stroke stats confirm this, showing that he only lost a respectable 0.18 strokes per stroke.  If Tom was interested in where he lost strokes for the round, he would see that he lost the most in this category, which is useful information.  However, if Tom is tracking his skill on shots in that distance range, he will likely find that his results are respectable.  If he wants to work in practice on his weakest skill, it is the 101-150 category at -0.47 per stroke. But if he consistently expects to make about 18 strokes per round from 0-50 yards (as opposed to only 4 shots from 101-150), this is having a bigger impact on his score because of the number of times he has to make that kind of shot in a round. Again, each type of statistic offers a unique, valuable perspective on his game.

The average pro in the average tournament takes 29 putts, 10 shots from 0 to 100 yards, 18 shots over 101 yards, and slightly over 14 drives.  For golfers of different ability levels and with varying skill in different categories, those numbers will vary dramatically.  In all cases, number of shots taken in a given category can vary drastically from round to round.

Another useful result of per stroke stats is their ability to put each shot into context, judging it in relation to various benchmarks.  For example, for any shot during a round you can know what result will be better or worse than average.  Once you know your per stroke averages in any category, you can use those values to accurately measure each shot in relation to your average result.  For example, after hitting a shot from the fairway 140 yards from the pin, your SG record-a-round mobile interface will immediately tell you your strokes gained value for that shot.  Once you know your per stroke average in the 101-150 category, you can use your result to directly compare your shot to your own average.

Eventually, SGG will be able to tell you instantly the quality of a given shot: was it a scratch level shot, a 10 handicap level shot, or a 20 handicap level shot?  Strokes gained per stroke stats makes this type of analysis possible.

Hopefully I have been able to adequately explain the difference between per round and per stroke strokes gained stats, and have shown that each is valuable in their own right.  Soon, you will find that all of this is not at all complicated.  Once you have become better acquainted with strokes gained statistics, you will discover the same thing we have: they are simple, elegant, exceptionally accurate, useful, flexibly applied to any aspect of the game, and ever-expanding.

 

 

 

 

 

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