Course rating, slope?

[iacas]

1 minute ago, DaveP043 said:

After reading all that @iacas just wrote (I didn't want to quote the whole thing), I can understand and agree with the logic, when using the negative index to calculate on-course handicaps for any kind of competition.  Where I'm still puzzling through things is in the computation in the opposite direction, in in the use of "under par"  scores in determining the index.  I'll keep noodling, and if I can explain my confusion any more clearly, I'll do it.  

Because for differentials on the plus side, they get it wrong.

http://www.ongolfhandicaps.com/2012/08/why-slope-handicap-system-doesnt-work.html

They used to have an article called "Slope on the Plus Side of Scratch" and I remember reading it, but I don't think it exists anymore.

IMO, for negative differentials, they should flip the 113/slope part of the math to make it slope/113. So if you shoot a 67 on a 72.0/150, that's -5 * 150/113, instead of -5 * 113/150.

We actually got that "wrong" the when we originally wrote up this article:

https://thesandtrap.com/b/the_numbers_game/calculating_the_handicap_indeces_of_the_pros

[mcanadiens]

5 hours ago, hilmar2k said:

I don't think I've even seen a course with a slope as low as 108. I think the lowest I've ever played is a 114, and it's a ridiculously easy course...for anyone. I feel like I'm cheating when I play there. Virtually all the courses I play are ~120.

That said, Hardspoon is correct.

We got a course that beats that like a drum. Community Dales Course is a 63.0 and 102. Awesome course for beginners at a tick under 5,000 yards. I still play it once in awhile. Granted my score expectations are a bit different from normal. 

 

[Rulesman]

@DaveP043 

 

Please don't because I understood iacas perfectly (as a golfer from a non-slope system - at the moment) but you might start confusing me   

Edited August 1, 2016 by Rulesman

[Aflighter]

1 hour ago, No Mulligans said:

Higher slope means "gets easier faster for better golfers".

I don't know what you mean by "easier faster".  And if I'm reading this correctly, higher slopes are easier for better golfers than lower slopes.  Or, for example a better golfer is expected to score better on a 72/140 than a 72/110.  What?  I'm very confused.

Thats not right.Higher slope does mean tougher no matter what your hcp.Give you example.A course with rating/slope of 71.5/135 would mean for a scratch golfer his score to equate to par would be almost 74.From experience with this is say you shot 72, well you shot over par by .5 stokes but then you figure that slope.Since its not 113 which is what is standard , you subtract 113 from that 135 and get 2.2.Now you add that 2.2 to the 71.5. 73.7 is par for scratch golfer.Therefore your 72 is like 1.7 under par.

[iacas]

5 minutes ago, Aflighter said:

Thats not right.Higher slope does mean tougher no matter what your hcp.Give you example.A course with rating/slope of 71.5/135 would mean for a scratch golfer his score to equate to par would be almost 74.From experience with this is say you shot 72, well you shot over par by .5 stokes but then you figure that slope.Since its not 113 which is what is standard , you subtract 113 from that 135 and get 2.2.Now you add that 2.2 to the 71.5. 73.7 is par for scratch golfer.Therefore your 72 is like 1.7 under par.

Huh? That's not even close to correct.

A 72 on a 71.5/135 course is a 0.5 * 113/135 = 0.4 differential. Eventually that'll be multiplied by 0.96.

You never subtract (or add) 113. That's always a divisor or dividend.

P.S. Are you just trolling, @Aflighter? Because 135-113 = 22, not 2.2.

[Hardspoon]

12 minutes ago, Aflighter said:

you subtract 113 from that 135 and get 2.2.

[Aflighter]

5 minutes ago, iacas said:

Huh? That's not even close to correct.

A 72 on a 71.5/135 course is a 0.5 * 113/135 = 0.4 differential. Eventually that'll be multiplied by 0.96.

You never subtract (or add) 113. That's always a divisor or dividend.

Your right.Sum reason I thought slope added more to par than it does.Must have missed  decimal point or something.On a slope of 139 it only adds .8 strokes to par.

[iacas]

Just now, Aflighter said:

Your right.Sum reason I thought slope added more to par than it does.Must have missed  decimal point or something.On a slope of 139 it only adds .8 strokes to par.

Slope adds nothing to par. The two have nothing to do with one another.

Slope is an entirely different number than the course rating, too: at every score, a given slope changes the differentials by a different amount from a given set of tees.

[Aflighter]

1 minute ago, iacas said:

Slope adds nothing to par. The two have nothing to do with one another.

To figure out the hcp differential it does.I shot a 76 on  72.0/139 and the differential was 3.2.Means I shot 3.2 over par instead of 4.

[iacas]

4 minutes ago, Aflighter said:

To figure out the hcp differential it does.I shot a 76 on  72.0/139 and the differential was 3.2.Means I shot 3.2 over par instead of 4.

No, it doesn't. You shot 4 over par (assuming the course was a par 72).

(76-72.0) * 113/139 = 3.3.
3.3 * 0.96 = 3.2.

Your differential that day was 3.2. It doesn't mean you shot 3.2 over par. You cannot shoot a fraction of a stroke, and there's no adding or subtracting 113.

Had you shot 90 rather than a gap of 0.7 or 0.8 between your score and your differential, you'd have seen a gap of 3.4 or 4 strokes, depending on when you want to apply the 0.96 multiplier.

[Club Rat]

4 minutes ago, Aflighter said:

To figure out the hcp differential it does.I shot a 76 on  72.0/139 and the differential was 3.2.Means I shot 3.2 over par instead of 4.

No, the differential is the number used in handicap calculation.

Erik just replied as I was typing. He's probably already beat me to the full explanation.

[Aflighter]

2 minutes ago, Club Rat said:

No, the differential is the number used in handicap calculation.

Erik just replied as I was typing. He's probably already beat me to the full explanation.

Yeah thats what i mean.The differential is what counts toward hcp, not the actual strokes over par.

[No Mulligans]

I finally understand @iacas 's logic.  My problem was looking at how the slope affects a round under par and the resulting differential.  But looking at it from how it affects a course rating makes sense.

Also, the below statement I agree with and would correct what has been my issue and confusion the entire time I've discussed this issue on this forum.

39 minutes ago, iacas said:

IMO, for negative differentials, they should flip the 113/slope part of the math to make it slope/113. So if you shoot a 67 on a 72.0/150, that's -5 * 150/113, instead of -5 * 113/150.

[iacas]

10 minutes ago, Aflighter said:

Yeah thats what i mean.The differential is what counts toward hcp, not the actual strokes over par.

Okay, but please note that this is wrong. Your differential below is 0.4, not 1.7 or whatever you're trying to suggest it is.

40 minutes ago, Aflighter said:

Thats not right.Higher slope does mean tougher no matter what your hcp.Give you example.A course with rating/slope of 71.5/135 would mean for a scratch golfer his score to equate to par would be almost 74.From experience with this is say you shot 72, well you shot over par by .5 stokes but then you figure that slope.Since its not 113 which is what is standard , you subtract 113 from that 135 and get 2.2.Now you add that 2.2 to the 71.5. 73.7 is par for scratch golfer.Therefore your 72 is like 1.7 under par.

These things are pretty simple math, so let's try not to screw 'em up.

[Rulesman]

24 minutes ago, Aflighter said:

Yeah thats what i mean.The differential is what counts toward hcp, not the actual strokes over par.

Par has nothing to do with anything associated with handicapping or course rating.

Par is simply the sum of the par of all 18 holes.

A course of 18 300 yard par 4s has a course par of 72

A course of 18 400 yard par 4s has a course par of 72

BUT

the first course would have a Scratch Course Rating of about 66.

the second course would have a Scratch Course Rating of about 74.

The Bogey rating and therefore the slope for each course would depend of the difficulty of the course for the bogey player relative to the scratch player playing the same course. 

 

Edited August 1, 2016 by Rulesman

[Aflighter]

5 minutes ago, iacas said:

Okay, but please note that this is wrong. Your differential below is 0.4, not 1.7 or whatever you're trying to suggest it is.

These things are pretty simple math, so let's try not to screw 'em up.

Yeah im sorry for saying hardspoon was wrong.From what im seeing, the higher you score on same course the differential isnt as penal.An 89 was 15.4 differential but an 81 was an 8.4 instead of being 7.4.

[Club Rat]

I made a couple of spreadsheets years ago.

One is for calculating handicaps and the other is for calculating course handicaps.

The players course handicaps spreadsheet works well on a phone when looking up multiple players at different tees.

If anyone would like a copy, send me a PM

[DaveP043]

1 hour ago, iacas said:

IMO, for negative differentials, they should flip the 113/slope part of the math to make it slope/113. So if you shoot a 67 on a 72.0/150, that's -5 * 150/113, instead of -5 * 113/150.

Now we're in complete agreement.  See post # 60