'Standard difficulty' slope is 113, why?

[tfro]

I'm curious why 113 was picked to be the slope of a 'standard difficulty' course. It seems like it would have made more sense to make 100 the standard and just adjust how you determine a course's slope accordingly.

 

Anyone know the history behind this?

[Newby]

When I introduced the system in 1982, the theoretical average Slope Rating was 113 because USGA data showed that scores go up on average 1.13 strokes per handicap stroke. The actual average Slope Rating is 120. The majority of courses in coastal states have Slopes of 121 and higher. Many Slopes lower than 118 are mid-American public courses. The lowest is 55 (short par-3 course), and the highest is 155

[i]Dean Knuth, Golf Digest Professional Advisor. Former senior director of the USGA handicap department, Knuth invented today's USGA Course Rating and Slope system[/i]

[tfro]

Thanks, that's what I was looking for, I should have known to look at his site.

[grabthepin]

Me too - I was thinking Dean Knuth had moved to England.


It's still a straight line btw.

[Newby]

[quote name='Mainlinegolfer' date='01 June 2010 - 05:00 PM' timestamp='1275408040' post='2480006']
Newby, without quotation marks, when I first starting reading the statement (in first person), I thought you [i]were [/i]Dean Knuth. lol
[/quote]

That's why I put the credit at the end rather than at the top.

[Sawgrass]

I find all of this interesting, but to the O.P.'s point, I believe Mr. Knuth would have created a system which was more easily understood by Average Joe Golfer if Mr. Kunth had instead used an arbitrary base number of 100 as the standard by which differentials are adjusted.

If the standard slope is 113, and you shot 90 on the hypothetical Nirvana course (which is a hypothetical 130 slope/70.0 rating) your differential would be (90-70) X 113/130, or 17.4. Alternately, if the base-100 slope system was used, the slope of Nirvana would be 115 (still 15% higher than standard) and the differential would be (90-70) X 100/115, still 17.4. But it would be easier to see and understand that Nirvana is 15% more challenging than standard (115/100 vs. 130/113) for bogie golfers to play.

I should add that while I just said that, it doesn't matter in the least. And the last thing golf needs is a change in the math.

[Newby]

[quote name='Mainlinegolfer' date='01 June 2010 - 09:19 PM' timestamp='1275423555' post='2480523']
[quote name='jontyc' date='01 June 2010 - 12:27 PM' timestamp='1275409628' post='2480070']
Me too - I was thinking Dean Knuth had moved to England.

It's still a straight line btw.
[/quote]

You're right, of course, but the (straight) line still "slopes." lol

[quote name='Newby' date='01 June 2010 - 12:57 PM' timestamp='1275411459' post='2480123']
[quote name='Mainlinegolfer' date='01 June 2010 - 05:00 PM' timestamp='1275408040' post='2480006']
Newby, without quotation marks, when I first starting reading the statement (in first person), I thought you [i]were [/i]Dean Knuth. lol
[/quote]

That's why I put the credit at the end rather than at the top.
[/quote]

Maybe, I'm not an English grammar teacher, but I'm not sure that's the correct way to punctuate a quotation. I thought quotation marks were used (short quotation) or indentation (more than a few lines). Therefore, it seemed Mr. Knuth was writing (apparently I was not alone).
[/quote]

There is only one rule in English grammar and that is that there are no fixed rules in English grammar.

However, I do usually follow the [i]convention[/i] of using quotation marks. But in this case I thought it would be amusing not to.

[Sawgrass]

I admit to being fooled and amused, in that order.

--------------

So apparently we now have two important British statesmen communicating on the rules of grammar.

Mr. Churchill's famous quote when challenged about ending a sentence in a prepostion: "This is the sort of bloody nonsense up with which I will not put!"

And now Mr. Newby's "There is only one rule in English grammar and that is that there are no fixed rules in English grammar. "

You really have to love this site!


[color="#ff0000"] [/color]

[AZPhys13]

Good to know. When I was younger, I always connected a higher slope with a greater uphill battle.

For the record, "straight line" is redundant as my high school geometry teacher always stressed.

[larrybud]

[quote name='Mainlinegolfer' date='01 June 2010 - 12:00 PM' timestamp='1275408040' post='2480006']
Newby, without quotation marks, when I first starting reading the statement (in first person), I thought you [i]were [/i]Dean Knuth. lol


BTW, for those of you unfamiliar with the concept and rationale for slope rating in addition to course handicap, because the line goes up by 1.13 strokes per handicap stroke (i.e. not a straight line), it has a slope; that's why it is called "Slope".
[/quote]
Without getting too technical, a flat straight line also has a slope... of 1.

In addition, slope (as in golf rating slope) IS a straight line. I.e., it's a linear formula (slope/113). It's not logrhythmic.

[teejaywhy]

[quote name='larrybud' date='08 June 2010 - 10:03 AM' timestamp='1276016618' post='2495053']
Without getting too technical, a flat straight line also has a slope... of 1.

[/quote]

Well actually...

A line with a slope of 1 is a 45 degree angle (from horizontal).

A flat line (horizontal) has a slope of 0.

A vertical line has a slope that is undefined.

[elunoputter]

[quote name='Sawgrass' date='01 June 2010 - 02:30 PM' timestamp='1275417015' post='2480303']
I find all of this interesting, but to the O.P.'s point, I believe Mr. Knuth would have created a system which was more easily understood by Average Joe Golfer if Mr. Kunth had instead used an arbitrary base number of 100 as the standard by which differentials are adjusted.

If the standard slope is 113, and you shot 90 on the hypothetical Nirvana course (which is a hypothetical 130 slope/70.0 rating) your differential would be (90-70) X 113/130, or 17.4. Alternately, if the base-100 slope system was used, the slope of Nirvana would be 115 (still 15% higher than standard) and the differential would be (90-70) X 100/115, still 17.4. But it would be easier to see and understand that Nirvana is 15% more challenging than standard (115/100 vs. 130/113) for bogie golfers to play.

I should add that while I just said that, it doesn't matter in the least. And the last thing golf needs is a change in the math.
[/quote]


you are leaving off the rest of the formula though...you are only using the best 10 of 20 and THEN you do the x .96 which affects higher handicap people more. It really doesn't matter what the base number is since the final result is then put up against the slope chart which is designed to see how many strokes the handicap player would need against a scratch player to come up with a tie theoritically.

[Sawgrass]

[quote name='elunoputter' date='08 June 2010 - 05:18 PM' timestamp='1276031932' post='2495802']
[quote name='Sawgrass' date='01 June 2010 - 02:30 PM' timestamp='1275417015' post='2480303']
I find all of this interesting, but to the O.P.'s point, I believe Mr. Knuth would have created a system which was more easily understood by Average Joe Golfer if Mr. Kunth had instead used an arbitrary base number of 100 as the standard by which differentials are adjusted.

If the standard slope is 113, and you shot 90 on the hypothetical Nirvana course (which is a hypothetical 130 slope/70.0 rating) your differential would be (90-70) X 113/130, or 17.4. Alternately, if the base-100 slope system was used, the slope of Nirvana would be 115 (still 15% higher than standard) and the differential would be (90-70) X 100/115, still 17.4. But it would be easier to see and understand that Nirvana is 15% more challenging than standard (115/100 vs. 130/113) for bogie golfers to play.

I should add that while I just said that, it doesn't matter in the least. And the last thing golf needs is a change in the math.
[/quote]


you are leaving off the rest of the formula though...you are only using the best 10 of 20 and THEN you do the x .96 which affects higher handicap people more. It really doesn't matter what the base number is since the final result is then put up against the slope chart which is designed to see how many strokes the handicap player would need against a scratch player to come up with a tie theoritically.
[/quote]

I left off lots of things, but they weren't relevant to my particular point, which is that a nominal slope of 100 for the standard course instead of 113 would more easily allow us to determine how hard a new course is. It's easier to divide in your head by 100 than by 113. At least it is for me.

[Newby]

[quote name='Sawgrass' date='01 June 2010 - 10:47 PM' timestamp='1275428842' post='2480686']
I admit to being fooled and amused, in that order.

--------------

So apparently we now have two important British statesmen communicating on the rules of grammar.

Mr. Churchill's famous quote when challenged about ending a sentence in a prepostion: "This is the sort of bloody nonsense up with which I will not put!"

And now Mr. Newby's "There is only one rule in English grammar and that is that there are no fixed rules in English grammar. "

You really have to love this site!

[/quote]

Try this one, my favourite

`When [i]I[/i] use a word,' Humpty Dumpty said in rather a scornful tone, `it means just what I choose it to mean -- neither more nor less.'

[tfro]

[quote name='Sawgrass' date='08 June 2010 - 04:39 PM' timestamp='1276033187' post='2495866']
[quote name='elunoputter' date='08 June 2010 - 05:18 PM' timestamp='1276031932' post='2495802']
[quote name='Sawgrass' date='01 June 2010 - 02:30 PM' timestamp='1275417015' post='2480303']
I find all of this interesting, but to the O.P.'s point, I believe Mr. Knuth would have created a system which was more easily understood by Average Joe Golfer if Mr. Kunth had instead used an arbitrary base number of 100 as the standard by which differentials are adjusted.

If the standard slope is 113, and you shot 90 on the hypothetical Nirvana course (which is a hypothetical 130 slope/70.0 rating) your differential would be (90-70) X 113/130, or 17.4. Alternately, if the base-100 slope system was used, the slope of Nirvana would be 115 (still 15% higher than standard) and the differential would be (90-70) X 100/115, still 17.4. But it would be easier to see and understand that Nirvana is 15% more challenging than standard (115/100 vs. 130/113) for bogie golfers to play.

I should add that while I just said that, it doesn't matter in the least. And the last thing golf needs is a change in the math.
[/quote]


you are leaving off the rest of the formula though...you are only using the best 10 of 20 and THEN you do the x .96 which affects higher handicap people more. It really doesn't matter what the base number is since the final result is then put up against the slope chart which is designed to see how many strokes the handicap player would need against a scratch player to come up with a tie theoritically.
[/quote]

I left off lots of things, but they weren't relevant to my particular point, which is that a nominal slope of 100 for the standard course instead of 113 would more easily allow us to determine how hard a new course is. It's easier to divide in your head by 100 than by 113. At least it is for me.
[/quote]

And that was the exact point of me starting the thread. 100 is a heck of a lot easier to divide by than 113, so there I figured there had to be a reason for 113 to be picked. And it looks like there was a reason, although I don't think it's a very good reason.

[larrybud]

[quote name='tjy355' date='08 June 2010 - 05:09 PM' timestamp='1276031393' post='2495779']
[quote name='larrybud' date='08 June 2010 - 10:03 AM' timestamp='1276016618' post='2495053']
Without getting too technical, a flat straight line also has a slope... of 1.

[/quote]

Well actually...

A line with a slope of 1 is a 45 degree angle (from horizontal).

A flat line (horizontal) has a slope of 0.

A vertical line has a slope that is undefined.
[/quote]
Oops, you're right!