Strokes Gained Standard Deviations on the PGA Tour

[iacas]

I asked Mark Broadie the question after guessing on the phone with John Graham (I was within 0.5 on all of them and within 0.1 on driving).

I have my own conclusions here, but what do you see? Any surprises? Any conclusions? Any thoughts?

[dennyjones]

I expected the strokes gained for putting and approach shots but would have guessed that driving would be higher also.   I believe it is understood that the weeks that the players win they hit better approach shots and putt better but usually drive the ball better too.  

[iacas]

4 hours ago, dennyjones said:

I expected the strokes gained for putting and approach shots but would have guessed that driving would be higher also.   I believe it is understood that the weeks that the players win they hit better approach shots and putt better but usually drive the ball better too.  

Remember it's standard deviation round to round.

Good drivers don't often just drive it 30 yards shorter or farther or become dramatically more or less wild week-to-week. Driving is a pretty "stable" skill round to round.

Around the greens appears to be pretty stable in part because… there aren't that many SG ATG. The leader last year was at less than +0.6 SG ATG.

They hit a lot of greens, and have a low O-Value for ATG shots.

[Vinsk]

7 hours ago, iacas said:

Remember it's standard deviation round to round.

Good drivers don't often just drive it 30 yards shorter or farther or become dramatically more or less wild week-to-week. Driving is a pretty "stable" skill round to round.

Around the greens appears to be pretty stable in part because… there aren't that many SG ATG. The leader last year was at less than +0.6 SG ATG.

They hit a lot of greens, and have a low O-Value for ATG shots.

Along this, is putting less ‘stable’ due to the conditions of the greens being significant? I mean, fairway condition doesn’t play a large effect on driving (weather does, yes)?And even a dry, wide open course may suit well for ball striking but a bumpy, wavy green can wreak havoc on even the best putters. Am I way off?

[iacas]

48 minutes ago, Vinsk said:

Along this, is putting less ‘stable’ due to the conditions of the greens being significant? I mean, fairway condition doesn’t play a large effect on driving (weather does, yes)?And even a dry, wide open course may suit well for ball striking but a bumpy, wavy green can wreak havoc on even the best putters. Am I way off?

I think it's simply because putting involves so much luck. Some days they all go in, some days they all miss.

That can lead to a high variance in the strokes gained.

[DeadMan]

I don't quite get what this is comparing. Is it comparing the rounds of each player to his average?

[iacas]

3 hours ago, DeadMan said:

I don't quite get what this is comparing. Is it comparing the rounds of each player to his average?

What do you mean?

You know what a standard deviation is, right?

Quote

In statistics, the standard deviation (SD, also represented by the lower case Greek letter sigma σ or the Latin letter s) is a measure that is used to quantify the amount of variation or dispersion of a set of data values. A low standard deviation indicates that the data points tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the data points are spread out over a wider range of values.

So, if a player has a SG:P of +0.450 (top 20 last year IIRC), but the standard deviation is 1.7, that means that about 68% of his rounds are going to be within +2.15 and -1.25. And since his average is so small (despite being at one of the extremes), that putting is pretty highly fluctuating: a top-20 guy at +0.450 will fairly often see back-to-back rounds of almost +4 to -3 strokes gained putting (that's about two standard deviations from his average. Seven shot swings from putting alone are pretty remarkable.

Compare that to, say, Dustin Johnson at 0.919 SG:OTT. The standard deviation of OTT is only 1.1 - Dustin will vary from about +2 to about -0.2. That's a lot less fluctuation round to round.

[DeadMan]

12 minutes ago, iacas said:

What do you mean?

You know what a standard deviation is, right?

So, if a player has a SG:P of +0.450 (top 20 last year IIRC), but the standard deviation is 1.7, that means that about 68% of his rounds are going to be within +2.15 and -1.25. And since his average is so small (despite being at one of the extremes), that putting is pretty highly fluctuating: a top-20 guy at +0.450 will fairly often see back-to-back rounds of almost +4 to -3 strokes gained putting (that's about two standard deviations from his average. Seven shot swings from putting alone are pretty remarkable.

Compare that to, say, Dustin Johnson at 0.919 SG:OTT. The standard deviation of OTT is only 1.1 - Dustin will vary from about +2 to about -0.2. That's a lot less fluctuation round to round.

I didn't understand what the standard deviation was of. I get that it's comparing a player to himself after that explanation.

After that, I'm not sure any of these are all that surprising. Maybe I figured that SG: around the green would have a smaller standard deviation, but I'm not even sure of that. Makes total sense that putting is going to have the biggest variation from round to round. Makes sense that approach will also have variations, because hitting one shot to 8 feet instead of 33 feet will be ~.5 strokes gained. A couple of really good shots instead of average shots will move the needle fast there.

[iacas]

49 minutes ago, DeadMan said:

After that, I'm not sure any of these are all that surprising. Maybe I figured that SG: around the green would have a smaller standard deviation, but I'm not even sure of that. Makes total sense that putting is going to have the biggest variation from round to round. Makes sense that approach will also have variations, because hitting one shot to 8 feet instead of 33 feet will be ~.5 strokes gained. A couple of really good shots instead of average shots will move the needle fast there.

Yes, and you have about 14-16 or so of them.