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# Slope- Why not %

Adding "slope" to the USGA handicap system was a big improvement, but why did they decide to call it "slope" as opposed to percent (or something that we are familiar with)?

i.e. a SLOPE of 113 means that your COURSE HANDICAP will be 100% of your INDEX (rounded to the nearest whole number).  Why doesn't the USGA refer to a course with a slope of 113 as 100 (percent)?  Are there any advantages of having slopes range from 55-155 as opposed to 49 to 137%?

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I don't know the answer, but I thought it had to do with what a linear graph of how difficult the course would be for a scratch vs. a bogey player.

Picture a line graph and on the left end of the line,  you have the difficulty on the given course for a scratch player.  Then on the other end you have the course's difficulty for a bogey player.  If the difficulty is reasonably the same, there won't be much 'rise' or 'slope' in the line.  But if the course is much harder for a bogey than for a scratch, the slope of the line will be more significant and carry a greater number value.

Probably has something to do with the slope = mx + b and rise/run that we leaned (and quickly forgot) in algebra a hundred years ago.

It's the slope of the line that connects the scratch golfer to the bogey golfer, so "slope" is the appropriate name.

Your idea to call it a percentage is just doing the 113/x math, but that'd be an extra step in how course slope is determined, and it'd feel like players are getting "extra" strokes or being robbed of "strokes" when in reality the "handicap index" don't have units.

Quote:
Originally Posted by Meltdwhiskey

I don't know the answer, but I thought it had to do with what a linear graph of how difficult the course would be for a scratch vs. a bogey player.

Picture a line graph and on the left end of the line,  you have the difficulty on the given course for a scratch player.  Then on the other end you have the course's difficulty for a bogey player.  If the difficulty is reasonably the same, there won't be much 'rise' or 'slope' in the line.  But if the course is much harder for a bogey than for a scratch, the slope of the line will be more significant and carry a greater number value.

Probably has something to do with the slope = mx + b and rise/run that we leaned (and quickly forgot) in algebra a hundred years ago.

Sorry, the math teacher in me just can't let this stand.  It is y = mx + b where m is the slope and b is the y-intercept (the point on the y-axis where the line crosses it).  But you get full credit on slope being rise over run.

Quote:
Originally Posted by iacas

It's the slope of the line that connects the scratch golfer to the bogey golfer, so "slope" is the appropriate name.

Your idea to call it a percentage is just doing the 113/x math, but that'd be an extra step in how course slope is determined, and it'd feel like players are getting "extra" strokes or being robbed of "strokes" when in reality the "handicap index" don't have units.

Yes, my idea is to do the 113 math so the player simply has to multiply by the percentage to compute HC.  I don't follow how that would be an extra step to compute the course slope?  With my idea, there would be no reason to have to know the course slope as knowing the % would be enough.  I really don't see the difference other than the fact that more people might understand how to convert their index to a course HC.

In terms of getting "extra" strokes or being robbed of "strokes" this happens already- this is a good thing.  Any time the slope is over 113, there is the potential for "extra" strokes and anytime it is less, there is the potential to be robbed of "strokes"  This makes sense as a high HC needs extra strokes on harder courses and fewer strokes on easier course.

Calling it % instead of slope doesn't change the mathematical outcome, it simply puts it in a term more people are already familiar with.  To compute course HC, you would multiply by the course % rather than slope/113.  I.e. if a course currently has a slope of 124, I would suggest calling that 110%.  So, if you were a 20.0 index, you would multiply by 1.10 to get a HC of 22 as opposed to 124/113 to get a HC of 22.

Internally, the USGA could still compute their slope figure with a "neutral" slope being 113 if they wanted, but then just convert this to a published % that more people would understand.  I realize that there a people on this board who understand how to compute their course HC without looking at a chart or using an online calculator, but most players with handicaps are pretty clueless about this.

So the player multiplies by 100 / 94.1 instead of 120 / 113....... Lots easier.

I gotta say though, if I worked as hard on my golf game as you do trying to find ways to change the game itself, I'd probably be a helluva lot better player than I am!
Edited by David in FL - 8/9/13 at 10:26pm
Quote:
Originally Posted by MEfree

I don't follow how that would be an extra step to compute the course slope?

It would be an extra step at the ratings level - i.e. internally, the ratings (the actual set of individual hole characteristic measurements) would still spit out a number like "137" and then the local golf association would have to take the extra step of doing the math. You'd only bother do that if the percentage was somehow simpler or made more sense, and it does not.

Furthermore, I think it would make things more complicated. Currently, to determine your differential, you do 113/slope. To find your handicap, it's slope/113. You simply reverse the side the 113 is on. Your proposal would have people taking their index and multiplying or dividing by a number that's larger or smaller than 1.0, and in my experience, people have a hard time "dividing by 87%." (They don't seem to get how dividing something can make a number larger.) It conceptually doesn't make as much sense to them as the current system.

Quote:
Originally Posted by MEfree

I don't follow how that would be an extra step to compute the course slope? With my idea, there would be no reason to have to know the course slope as knowing the % would be enough.

I addressed the "extra step" bit above.

Do you read what you write? What's the difference - players have to know a number. In your system, they have to know "87" or whatever. In the current one, they have to know "137" or whatever. Players have to know the same number of things.

Quote:
Originally Posted by MEfree

Internally, the USGA could still compute their slope figure with a "neutral" slope being 113 if they wanted, but then just convert this to a published % that more people would understand.  I realize that there a people on this board who understand how to compute their course HC without looking at a chart or using an online calculator, but most players with handicaps are pretty clueless about this.

I don't think that more people would understand it. I don't think that the current system is difficult to understand. In fact, as stated above, I think that more people would have a tougher time wrapping their brains around multiplying and dividing by the percentage than the way it's currently done.

Quote:
Originally Posted by turtleback

Sorry, the math teacher in me just can't let this stand.  It is y = mx + b where m is the slope and b is the y-intercept (the point on the y-axis where the line crosses it).  But you get full credit on slope being rise over run.

I imagine you are right about this, but the way the USGA calculates SLOPE RATING is really much easier mathematically-

(v) Slope Rating is the difference between the Bogey Rating and the USGA Course Rating multiplied by 5.381 for men and 4.24 for women. (See Definitions and 13-3f.) http://www.usga.org/Rule-Books/Handicap-System-Manual/Rule-13/#scrollTop:rules_browse_left=0.30601092896174864

So why did they pick 5.381 and 4.24 instead of 4.762 and 3.752?  Had they picked the later two numbers instead, then a slope of 113 would now be 100.

Quote:
Originally Posted by David in FL

So the player multiplies by 100 / 94.1 instead of 120 / 113....... Lots easier.

I gotta say though, if I worked as hard on my golf game as you do trying to find ways to change the game itself, I'd probably be a helluva lot better player than I am!

No- instead of multiplying by 120/133 you would multiply by 106/100 (or 1.06 or 106%)- Yes, I think that IS EASIER.  Do you really think it is just as easy to divide by 113 as opposed to 100?

Quote:
Originally Posted by iacas

It would be an extra step at the ratings level - i.e. internally, the ratings (the actual set of individual hole characteristic measurements) would still spit out a number like "137" and then the local golf association would have to take the extra step of doing the math. You'd only bother do that if the percentage was somehow simpler or made more sense, and it does not.

Furthermore, I think it would make things more complicated. Currently, to determine your differential, you do 113/slope. To find your handicap, it's slope/113. You simply reverse the side the 113 is on. Your proposal would have people taking their index and multiplying or dividing by a number that's larger or smaller than 1.0, and in my experience, people have a hard time "dividing by 87%." (They don't seem to get how dividing something can make a number larger.) It conceptually doesn't make as much sense to them as the current system.

I addressed the "extra step" bit above.

Do you read what you write? What's the difference - players have to know a number. In your system, they have to know "87" or whatever. In the current one, they have to know "137" or whatever. Players have to know the same number of things.

I don't think that more people would understand it. I don't think that the current system is difficult to understand. In fact, as stated above, I think that more people would have a tougher time wrapping their brains around multiplying and dividing by the percentage than the way it's currently done.

You gotta better explain to me what the extra step would be if the Men's multiplier was 4.762 and the Women's 3.752 instead of the current 5.381 & 4.24 because I don't see it.  Yes, people would still have to know the same number of things, but dividing (or multiplying) by 100 is easier than 113.  If you don't like the idea of %, here is what it could look like using 100 as your "neutral" slope instead of 113

 Current Slope New Slope 55 49 70 62 85 75 100 88 113 100 118 104 123 109 128 113 133 118 138 122 143 127 148 131 155 137

Current Course Handicap Calculation:

Index*(Slope/113)

New Course Handicap Calculation

Index*(Slope/100)

I fail to understand why dividing by 113 is easier than dividing by 100.  If someone has a valid reason, please explain.

While I imagine that very few people actually calculate their individual round indexes after playing, that too would be easier.

Current Round Index Calculation:

ESC Score-CR*(113/Slope)

New Round Index Calculation:

ESC Score-CR*(100/Slope)

Same number of steps using 100 instead of 113.  I know some people that can multiply and divide by 100 in their heads, but few who can do that with 113.  So my original questions stands, why did the USGA pick 113 as their baseline instead of 100?

MEfree, I don't have to explain anything. People are weirded out by the fact that dividing by 87% makes the number larger.

And if you add the 100 in there, it's basically no change over what we do now except for the sake of change.

So, like many of your conversations, this one is now clearly a non-starter. No point except that you want to change things.

I'm not saying that to be rude. You simply need to do a better job if stating your reasons earlier, and making them compelling. You've not done so here. Do it sooner and I won't feel the need to try to draw them out and participate.

P.S. you don't seem to give any credence that the internal numbers provide for a slope of 113. That's why the numbers work out. 113 was the derived number. It just came out that way. As in when courses are actually rated, they're done using certain figures, value ranges. 113 comes out that way. 100 would require conversion. The 5.381 isn't an arbitrary part, it's a result.
I think the back and forth on this thread is unnecessary... I see your point, MEfree. You take a step out of the equation for handicap calculation. But does it really matter? For those of us that know how to calculate a handicap manually (which isn't hard), we could care less... Would folks that have no idea how handicaps are calculated know the difference between a 0.973 rated course and a 1.061 rated course (compared to 110 vs 120)? Perhaps, but if they aren't avid enough golfers now to know how slope ratings work now, I wouldn't think it would matter...
Quote:
Originally Posted by turtleback

Sorry, the math teacher in me just can't let this stand.  It is y = mx + b where m is the slope and b is the y-intercept (the point on the y-axis where the line crosses it).  But you get full credit on slope being rise over run.

Ha! Yeah it has been a while. I butchered it. I could really do it up when I was 13 thothough.
Quote:
Originally Posted by iacas

MEfree, I don't have to explain anything. People are weirded out by the fact that dividing by 87% makes the number larger.

And if you add the 100 in there, it's basically no change over what we do now except for the sake of change.

So, like many of your conversations, this one is now clearly a non-starter. No point except that you want to change things.

I'm not saying that to be rude. You simply need to do a better job if stating your reasons earlier, and making them compelling. You've not done so here. Do it sooner and I won't feel the need to try to draw them out and participate.

P.S. you don't seem to give any credence that the internal numbers provide for a slope of 113. That's why the numbers work out. 113 was the derived number. It just came out that way. As in when courses are actually rated, they're done using certain figures, value ranges. 113 comes out that way. 100 would require conversion. The 5.381 isn't an arbitrary part, it's a result.

I wasn't advocating changing it now (given that some people understand the current system), but was wondering why they made the baseline 113 instead of 100 to begin with.  5.381 is a result of what exactly?

Quote:
Originally Posted by MEfree

I wasn't advocating changing it now (given that some people understand the current system), but was wondering why they made the baseline 113 instead of 100 to begin with.  5.381 is a result of what exactly?

It's a result of the math (and the ratings system) that leads to 113. 113 is the number they arrive at, and 5.381 is the result of that slope, not the other way around.

And why do you ask questions like "why do they call it slope instead of percent" when you can probably just write to the guy who built the handicap system via his site at http://popeofslope.com ?

http://www.popeofslope.com/courserating/

http://www.popeofslope.com/courserating/whatsin.html

http://www.popeofslope.com/courserating/slope.html

http://www.popeofslope.com/courserating/system.html

http://www.popeofslope.com/courserating/sysdev.html

http://www.popeofslope.com/courserating/whatsthis.html

http://www.popeofslope.com/courserating/whatsin.html

(Note that the formulas and things have changed over the years. The weighting of elements like yardage may be a fair bit different than in 1981, or 1991, etc. Every spring we go to meetings about the changes in how courses are to be rated.)

Quote:

Originally Posted by iacas

It's just math. The average scratch golfer isn't averaging par, or even par with the best 10 of his last 20, either.

You've still got it backwards. 5.381 is the result of the 113, not the other way around. As in "they got 113, and so to make that fit, it's 5.381." But regardless, that's not the topic here.

And now I'm done.

So where do they get the 113 from?  What I think they arrive at is what a "bogey golfer" will shoot on a course of "average" difficulty (in their 10 best rounds of 20).  That appears to be 21 over the course rating (which is what the "scratch golfer" will shoot).  This in then multiplied by 5.381 to get a slope of 113.  So these are the steps as I see them:

1.  Use multiple criteria to determine CR

2.  Use multiple criteria to determine Bogey Rating

3.  Subtract CR from BR

4.  Multiply the above result by 5.381 for Men and 4.24 for Women to get the Slope Rating (which is 113 for an average course)

Quote:

Originally Posted by iacas

It's a result of the math (and the ratings system) that leads to 113. 113 is the number they arrive at, and 5.381 is the result of that slope, not the other way around.

I think you are right if you are saying that 113 is the target and 5.381 is the resulting multiplier needed to reach that target.  i.e. 113= 21*X making X= 5.381 with 21 being the average a bogey golfer is over CR on the average course.  By the question still remains, why is the average course 113 and not 100?  I guess this is a question for pope of slope...at this point, if I had to take a guess, I think it might be something political like not wanting course to appear easy by having a two digit number- with 113 as the average, less people might realize that their 108 slope course is easier than average because they don't know what the average really is.

Edited by MEfree - 8/10/13 at 11:06pm
Quote:
Originally Posted by MEfree

if I had to take a guess, I think it might be something political like not wanting course to appear easy by having a two digit number- with 113 as the average, less people might realize that their 108 slope course is easier than average because they don't know what the average really is.

I will admit that it's somewhat amusing that you think that despite the well known published value of 113, and the fact that virtually EVERY course in their area will be more difficult in obvious ways, you think that there was some grand scheme to obscure and confuse golfers, particularly when that course is quite likely to have a much lower course rating. You don't see too many 74.2/105 courses.

This is just conjecture piled on top of what is quite literally a pointless discussion. I'm still done.

Who cares what is easier?  With calculators, both handheld and online, nobody does any actual math any more anyway, so it doesn't make any difference what numbers they use.  When entering scores, you enter either the total score or hole by hole score and the program or website does the figuring.  Same for  course handicap.  Much ado about nothing.

Quote:
Originally Posted by Fourputt

Who cares what is easier?  With calculators, both handheld and online, nobody does any actual math any more anyway, so it doesn't make any difference what numbers they use.  When entering scores, you enter either the total score or hole by hole score and the program or website does the figuring.  Same for  course handicap.  Much ado about nothing.

This is pretty much the reason the US did not switch to the metric system too.

Quote:
Originally Posted by boogielicious

This is pretty much the reason the US did not switch to the metric system too.

I always thought it was because none of us could imagine Peter, Paul and Mary singing "500 Kilometers Away From Home".

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