Micro Detection of Green Speeds

[Scott Stambaugh]

I had a member (average ability) comment to me today that he felt the practice green was faster than the greens on the course.  I told him that was unlikely, we discussed it for a few minutes and then I said we'd check it out.

Greens on the course 10'5", practice green 10'7".

Now, as most of my game continues on a downward spiral, I feel like my short game is still above-average.  Combine that with the fact that I spend most of my waking hours walking on, looking at and worrying about greens, my sense of green speed/consistency is pretty good.

I can tell the difference between 9' and 10', 10' and 11', 11' and 12'.  12' and 13' starts to get a bit harder. 

So, at what point are differences in green speeds detectible to you?  I doubt there is a person in the world who can detect a 2" difference in speed, right?

Scott

[Anthony Fowler]

Scott, I don't think your stimp is precise enough to accurately detect a 2 inch difference.  The standard error on any stimp reading is surely greater than that.  I don't even think the Pelz apparatus and protocol is that good.  2 inch difference using the tools we have at our disposal means no determinable difference.

[Rich Goodale]

Scott

If I were you I'd hire that member.  Just think of the cost savings you could make just in the reduction of stimpmeter purchases alone!

[Scott Stambaugh]

Scott, I don't think your stimp is precise enough to accurately detect a 2 inch difference.  The standard error on any stimp reading is surely greater than that.  I don't even think the Pelz apparatus and protocol is that good.  2 inch difference using the tools we have at our disposal means no determinable difference.

Not sure I understand you.

There is a 2" difference- It's quite easy to get a number.

What is the standard error of reading on a stimpmeter?

[Anthony Fowler]

Scott, I don't think your stimp is precise enough to accurately detect a 2 inch difference.  The standard error on any stimp reading is surely greater than that.  I don't even think the Pelz apparatus and protocol is that good.  2 inch difference using the tools we have at our disposal means no determinable difference.

Not sure I understand you.

There is a 2" difference- It's quite easy to get a number.

What is the standard error of reading on a stimpmeter?

Hi Scott,

I know that the 2 inch difference is measurable but it is probably not statistically significant.  If you tried to get a stimp reading 10 different times at 10 slightly different locations on your practice green, the readings would vary by more than a couple inches.  The standard error is the square root of the average squared deviation from the average reading, which is just a measure of how consistent your readings are.  One standard error from average should encompass roughly two-thirds of all your readings in this case.

If you are really interested to know if the practice green is different than the others, take 10 different readings from 10 different places on each, and I'd be happy to analyze the numbers for you.  My e-mail is fowler@mit.edu.

I would think that slight changes in slope and contour could easily account for more than 2 inches.  The standard procedure is to take a reading for 2 opposite directions and average them.  However, we know that if there is some slope, the downhill will add more length than the uphill will take away.  This means that the green will always stimp higher on a more tilted part of the green.

Anthony

[JMEvensky]

Didn't the USGA do some kind of study with various skill levels?I think only Tour-level Pro's and amateurs could distinguish speeds down to the foot.Higher handicaps didn't get close.

[Jeff_Brauer]

Reminds me of the story of some NBA star long ago (Dr. J?) who noticed in practice that his shots weren't going in as usual and "knew" the basket was low.  Turns out he was right and it was about an inch lower than standard.

Is there any possibility that this guy was pulling your leg or lucky?  A single stimp reading combines uphill and downhill putts, so he would experience differences depending on where he putted.

Could mowing the putting green first or last, shade, and even heavier foot traffic have affected this reading at that time of day?

My first inclination would be to tell the member that

A., All those things can affect the stimp, and

B., they just naturally vary as a result, and that's part of golf. 



Even with another $100K per year, I doubt a super could "guarantee" a closer spread of stimp readings from green to green, could they?

And, how can he even pull the putter back with that kind of thought going through his mind?  Is that any different than a 100 shooter knowing its 147 or 149 to the green with his range finder?  Does it help him make any putts, or just confuse him?

[rjsimper]

Lucky guess by a picky member.

No way to gauge the micro slopes between your measurements on the practice green and on the course, and I do agree with those who say that 2" has to be well within the margin of error when comparing two separate surfaces.

[Richard Choi]

Lucky guess by a picky member.

No way to gauge the micro slopes between your measurements on the practice green and on the course, and I do agree with those who say that 2" has to be well within the margin of error when comparing two separate surfaces.

Not much luck involved. He had a 50/50 chance that he got it right, just a flip of a coin.

2" difference on a green that is running at around 10' is less than 2% difference. There are not many scientific instruments that have error margin finer than 2%. With a fairly blunt tool like a Stimpmeter, there is no way you can detect a true 2% difference.

[SL_Solow]

Jeff;  it was Rick Mount of Purdue at the NCAA finals.

[Jeff_Brauer]

Yeah, I "knew" my memory was off by an inch.....

[John Moore II]

Back to the original question about how precisely can you determine green speed, I am not sure how I can. I would say anything below 7 or 8 is slow, between 8 and 11 moderate, and anything about 11 plainly freaking fast. Anything beyond simply definitions like that other than for consistency is foolish, I think. I could probably tell the difference between 8' and 9' or 8' and 7', maybe. Overall though, get them all reasonably the same and they are fine.

Going with the Error thing, yeah, 2" is almost nothing. A friend of mine had one of those Pelz True Roller things, and we used it on the green. If you started the ball from even 1/4" higher on the runner or 1/4" lower on the runner, it would miss the hole because of speed. Its the same deal with a Stimpmeter, unless you are perfect in where you start the ball on the runner (you're not, even with it marked, by the way) you will get slightly different readings each time. Roll 10 or even 25 balls on each green at different spots, etc and average each green. Then look at the whole course, I'd bet there is very little difference between them, maybe 1" or 2" over the whole course.

[Scott Stambaugh]

Lucky guess by a picky member.

No way to gauge the micro slopes between your measurements on the practice green and on the course, and I do agree with those who say that 2" has to be well within the margin of error when comparing two separate surfaces.

Not much luck involved. He had a 50/50 chance that he got it right, just a flip of a coin.

2" difference on a green that is running at around 10' is less than 2% difference. There are not many scientific instruments that have error margin finer than 2%. With a fairly blunt tool like a Stimpmeter, there is no way you can detect a true 2% difference.

That was my take all along.  I just want to get others thoughts on it.

The areas we check green speeds are at 0.1%-0.2% slope.  So, when I say 10'5", it's 10'6" downhill  and 10'4" uphill.  Obviously, when the greens are faster, the margin of difference is greater. 

A USGA agonomist in my area tells a funny story about how at the club he is a member at, they had to take a golf event indoors because of bad weather.  A putting contest broke out in a hallway of the clubhouse and he then had everyone try and guess what the carpet was 'stimping.'  No one came within 6 feet- it was running around 26...

Scott

[Pat Brockwell]

They did a study at Michigan State on golfers ability to detect speed differences.  Pros were better at it, but average players couldn't reliably discern the differences till it was at or above a foot.  I have found that different makes of balls can stimp differently. Pro V  fast, range balls slow, 2" to 3" difference on a 9' roll.  Try it, you know, peer review.

[Ian Larson]

Lets not forget the stimp is not a SPEEDOMETER for the members its a tool to maintain CONSISTENCY from green to green on the course

[Scott Stambaugh]

They did a study at Michigan State on golfers ability to detect speed differences.  Pros were better at it, but average players couldn't reliably discern the differences till it was at or above a foot.  I have found that different makes of balls can stimp differently. Pro V  fast, range balls slow, 2" to 3" difference on a 9' roll.  Try it, you know, peer review.

Interesting, I'll try and find that information.  I usually use Pro V's, I guess that could be posted in the "Golf Superstitions" thread as well. 

Lets not forget the stimp is not a SPEEDOMETER for the members its a tool to maintain CONSISTENCY from green to green on the course

I can't think of an occasion through the years when a member has asked me "What are they rollin' at?"  and I considered answering "Oh, they're consistent."  Like it or not, the stimpmeter is what it has become.

Scott

[Adam Clayman]

I wouldn't discount a guy just because his handi is high (or average ability). Remember the putting green is the only place mere mortals can come close to equating, in ability, with the Pros. Just the other day I noticed a difference of about half a foot between West Winds front nine and back nine greens. Now, I never would have that ability if it wasn't for caddying, and putting many hours, for money, with elderly gentlemen. BTW, those green sets were built in different eras and have entirely different sub-soils, wind flow and shade. The grass mix is also slightly different.


 

[TEPaul]

Some say that a good tour pro can detect a six inch differential in greenspeed particularly when it gets up there pretty high----where playablility gets really exponential with a slight speed differential increase.

To get used to this kind of thing I think one pretty much needs to be exposed to green testing for speed and pinnablility quite a bit. I know I sure have learned a lot over the years being one of the guys who tests speeds and pins for tournaments when I officiate.

But to consistently detect a .2 differential? No way.

[TEPaul]

Here's another interesting observation on testing green speeds. Some of the guys who test green speed and playablility a lot more than I do throw the ball instead of hitting it with a putter. There's no way at all I could do that and get much of a feel for speed. I have to putt balls.

[Scott Stambaugh]

I wouldn't discount a guy just because his handi is high (or average ability). Remember the putting green is the only place mere mortals can come close to equating, in ability, with the Pros. Just the other day I noticed a difference of about half a foot between West Winds front nine and back nine greens. Now, I never would have that ability if it wasn't for caddying, and putting many hours, for money, with elderly gentlemen. BTW, those green sets were built in different eras and have entirely different sub-soils, wind flow and shade. The grass mix is also slightly different.


 

Adam,

Your analogy of the putting green being the great equalizer is pretty good.  I haven't thought about it that way in a long time.  It reminds me when I was a teenager and used to play golf with a lot of seniors.  These guys could barely bunt the ball out of their own shadow but seemed to knock every putt in they looked at.

Here's another interesting observation on testing green speeds. Some of the guys who test green speed and playablility a lot more than I do throw the ball instead of hitting it with a putter. There's no way at all I could do that and get much of a feel for speed. I have to putt balls.

TEPaul,

Funny you mention that.  I was standing next to the 18th green on Friday morning at the 1998 U.S. Open at Olympic and watched as an official tossed a ball around that green while the golf course staff was doing their thing.  They continued to mow/roll/mow/roll/roll/roll/mow/mow until he deemed it perfect.  I think in this case, the ball didn't get tossed in the proper spot...

Scott