Nerdy Handicap question

[tlasher]

My buddies and I were trying to figure out what the differential would be for a 63 at the Byron Nelson yesterday.

 

the course rating is 77.5

slope is 147

 

so 63-77.5 = -14.5

 

now, would you multiply that by 113/147 OR by 147/113  ???

 

Seems to me that it makes sense to multiply by 147/113 to make the negative differential even bigger, representing the harder course with a big slope, but I also know I am probably wrong for some reason I don’t understand...maybe the fact that the difficulty is already cooked into the course rating and the slope is designed to make adjustments related to weaker players?

Edited May 14, 2021 by tlasher
Correction

[jvincent]

You multiply by 147/113.

 

EDIT: Oops, I was calculating course handicap, not differential.

Edited May 15, 2021 by jvincent

[Colin L]

 

9 hours ago, tlasher said:

My buddies and I were trying to figure out what the differential would be for a 63 at the Byron Nelson yesterday.

 

the course rating is 77.5

slope is 147

 

so 63-77.5 = -14.5

 

now, would you multiply that by 113/147 OR by 147/113  ???

 

Seems to me that it makes sense to multiply by 147/113 to make the negative differential even bigger, representing the harder course with a big slope, but I also know I am probably wrong for some reason I don’t understand...maybe the fact that the difficulty is already cooked into the course rating and the slope is designed to make adjustments related to weaker players?

Multiply by 113/147. as per the formula . Let the minus take care of itself.

 

Score Differential =  (Gross Adjusted score - Course Rating) X  113/Slope Rating

                              =(63-77.5) x 113/147

                                    = -11.1

 

NB  There could also be a Playing Conditions Calculation adjustment  to be made.

 

 

Edited May 15, 2021 by Colin L

[Shilgy]

17 minutes ago, Colin L said:

 

Multiply by 113/147. as per the formula . Let the minus take care of itself.

 

Score Differential =  (Gross Adjusted score - Course Rating) X  113/Slope Rating

                              =(63-77.5) x 113/147

                                    = -11.1

 

NB  There could also be a Playing Conditions Calculation adjustment  to be made.

 

 

Clearly the course is playing easy. Will definitely need a PCC adjustment.  😆

[Colin L]

1 hour ago, Shilgy said:

Clearly the course is playing easy. Will definitely need a PCC adjustment.  😆

 

I was only explaining how the numbers work, not commenting on  credibility. 😀

[Newby]

11 hours ago, tlasher said:

 

 

 

 

now, would you multiply that by 113/147 OR by 147/113  ???

 

Seems to me that it makes sense to multiply by 147/113 to make the negative differential even bigger, representing the harder course with a big slope, but I also know I am probably wrong for some reason I don’t understand...maybe the fact that the difficulty is already cooked into the course rating and the slope is designed to make adjustments related to weaker players?

You multiply the Handicap Index by 147/113 in order to get the player's Course Handicap. That applies the slope to the course being played.

In order to get the differential you have to 'de-slope' the score by multiplying by 113/147.

That makes the differential course neutral.

[tlasher]

6 hours ago, Newby said:

You multiply the Handicap Index by 147/113 in order to get the player's Course Handicap. That applies the slope to the course being played.

In order to get the differential you have to 'de-slope' the score by multiplying by 113/147.

That makes the differential course neutral.

I don’t doubt this is correct but the reason this confuses me is that if two players beat the differential by 10 shots on two different courses, while both will post a negative differential, the player who did it on the HIGHER slope course will post a negative differential of SMALLER magnitude, seemingly representing a round of lower skill.

 

am I making any sense?

[jvincent]

15 hours ago, jvincent said:

You multiply by 147/113.

 

EDIT: My bad, I was calculating course handicap, not differential.

[Shilgy]

15 minutes ago, tlasher said:

I don’t doubt this is correct but the reason this confuses me is that if two players beat the differential by 10 shots on two different courses, while both will post a negative differential, the player who did it on the HIGHER slope course will post a negative differential of SMALLER magnitude, seemingly representing a round of lower skill.

 

am I making any sense?

That issue has been discussed repeatedly…..and it sounds like an issue doesn’t it?  However, would you agree that two sets of scores 10 strokes apart should have the same variance in differential no matter the score? 
  For example….take a course rated 75.0 140 and have scores of 75 and 85. They would have differentials of 0.0 and 8.071.   Scores of 85 and 95 would be 8.071 apart.  If you go plus it should stay the same. Take that score of 75 and match it with a 65. Using 113/140 you get the same 8.071 difference.rather than the 12.39 you would get using 140/113.

 

Clear as mud?

Edited May 15, 2021 by Shilgy

[rogolf]

27 minutes ago, tlasher said:

I don’t doubt this is correct but the reason this confuses me is that if two players beat the differential by 10 shots on two different courses, while both will post a negative differential, the player who did it on the HIGHER slope course will post a negative differential of SMALLER magnitude, seemingly representing a round of lower skill.

 

am I making any sense?

Think of it another way - the adjustment to the score is to bring the differential to a standard slope rating of 113.  A differential made at a course with a slope rating of 147 needs to be reduced to the standard slope rating of 113.

[Newby]

8 hours ago, tlasher said:

I don’t doubt this is correct but the reason this confuses me is that if two players beat the differential by 10 shots on two different courses, while both will post a negative differential, the player who did it on the HIGHER slope course will post a negative differential of SMALLER magnitude, seemingly representing a round of lower skill.

 

am I making any sense?

No.

How do you beat 'the differential'. What do you mean by that expression?

 

Incidentally the Score Differential in simple terms is (Gross score - Course Rating) x (113/Slope) 

[Colin L]

9 hours ago, tlasher said:

I don’t doubt this is correct but the reason this confuses me is that if two players beat the differential by 10 shots on two different courses, while both will post a negative differential, the player who did it on the HIGHER slope course will post a negative differential of SMALLER magnitude, seemingly representing a round of lower skill.

 

am I making any sense?

 

 

Think course rating not slope rating  if you want to compare the performance of two golfers on different courses.  If Player A  has a 68 on a course CR 70  he has gone round in 2 strokes fewer than is expected of a scratch player.   If Player  B has a 71 on a course CR 73, he too has gone round In 2 strokes fewer than is expected of a scratch player.  In this example, scores of 68 and 71 are comparable; they represent the same level of performance.  What the slope ratings of these courses might be is irrelevant to that comparison (and pretty well irrelevant to players of that calibre in any case).

 

 

Edited May 15, 2021 by Colin L

[tlasher]

3 hours ago, Newby said:

No.

How do you beat 'the differential'. What do you mean by that expression?

 

Incidentally the Score Differential in simple terms is (Gross score - Course Rating) x (113/Slope) 

Sorry, meant to say beat course rating 

[Newby]

7 hours ago, tlasher said:

Sorry, meant to say beat course rating 

In that case your original question has omitted some significant points.

The combination of Course Rating and Slope has to be considered.

A high slope and low CR does not tell you enough about the 'difficulty' when compared to a low slope and a high CR. It then depends on the player's Handicap Index 

So all three pieces of information are needed to make the comparison between your two players on different courses. And that's what the Score Differential does.

Edited May 16, 2021 by Newby

[Shilgy]

I do understand the confusion from the op and others. Those of us not on the plus side side of handicap indexes have it so entrenched in our heads that a 140 slope course is intrinsically more difficult than a 120 slope course.  So it does seem to not make sense that on courses with a 72.0 course rating a 65 on a 120 slope course creates a lower differential than does the 65 scores on the 140 slope.

  But mathematically it makes sense and is logical for reasons often explained.

[tlasher]

Thanks all. learned a lot.  
 

now to go out and shoot some negative differential rounds to apply all this 😀