9-Hole competition differential

[rossh28]

Hi,

New here, I just had a question around 9 hole comps and the differential they give out as I can't seem to work mine out from any of the formulae on the internet.

Score: 38
HI: 2.9

F9 CR: 35.1
F9 Par: 35
F9 SR: 131

B9 CR: 34.8
B9 Par: 35
B9 SR: 130

And the differential which was produced by the system was 5.0 - any help is much appreciated!

 

[BubbaP]

In case this helps
https://forums.golfmonthly.com/threads/world-handicap-system-whs.104054/post-2341513

 

[rossh28]

In case this helps
https://forums.golfmonthly.com/threads/world-handicap-system-whs.104054/post-2341513

Thanks but unfortunately not, my B9 Course Handicap is 1 so that would be a 37 to give 75 and a 5.1 differential which is then modified by the course slope of 131 to give 4.4.

 

[mikejohnchapman]

Which 9 did you play - front or back?

It could be a problem about the way the score was entered if the competition was defined in such a way as to input 9 hole scores onto a course defined for 18 holes.

We have 9 hole loops which are defined as such and 18 hole course which are a combination of 2 loops. Providing the comp is set-up correctly the handicap GD is calculated correctly.

 

[jim8flog]

The guides for 9 hole scores can be found in the

https://www.congu.co.uk/wp-content/uploads/WHSDocs/Handicapping-Advice.pdf

Appendix I B. Page 31

 

[Colin L]

Why are you mentioning your Course Handicap when calculating a score differential?

 

[rosecott]

This should be the calculation for Front 9:

CH = ((HI ÷ 2 ) x (9-hole Slope ÷ 113)) + (9-hole CR – 9-hole Par)



2.9 131 35.1 35



1.45x1.159=1.68+0.1=1.69, rounded to 2

 

[Colin L]

Hi,

New here, I just had a question around 9 hole comps and the differential they give out as I can't seem to work mine out from any of the formulae on the internet.

Score: 38
HI: 2.9

F9 CR: 35.1
F9 Par: 35
F9 SR: 131

B9 CR: 34.8
B9 Par: 35
B9 SR: 130

And the differential which was produced by the system was 5.0 - any help is much appreciated!

When you play a 9 hole round, your score is scaled up to an 18 hole score by assuming a net par at each of 9 holes plus 1 stroke. You use the same holes as you have already played but without knowledge of the pars of those holes and the stroke index, it's not possible to tell you what your score differential was.

 

[Old Skier]

Am I on the wrong track here but we have 9 hole registered courses and slopes which show you exactly what your handicap course handicap is and it appears on the EG app. All this maths milarkey just makes a simple system difficult.

 

[rossh28]

When you play a 9 hole round, your score is scaled up to an 18 hole score by assuming a net par at each of 9 holes plus 1 stroke. You use the same holes as you have already played but without knowledge of the pars of those holes and the stroke index, it's not possible to tell you what your score differential was.

I think this is it so you double the F9 CR and as my F9 CH is 2 I get allocated a 38 on the back which gives a score of 76 against the rating of 70.2 which is 5.8 when adjusted for slope this becomes 5.0, thanks all.

 

[Colin L]

I think this is it so you double the F9 CR and as my F9 CH is 2 I get allocated a 38 on the back which gives a score of 76 against the rating of 70.2 which is 5.8 when adjusted for slope this becomes 5.0, thanks all.

That's it, except don't think of "on the back" as that might confuse. If you play the front 9 of am 18 hole course, the back 9 doesn't come into the scaling up. Correspondingly, if you play the back 9, the from 9 doesn't come into it. Think of it more simply as going round a nine hole course twice, the first time for real and the second time in your imagination. And the great thing about a golfer's imagination is that he can get very consistent: 1 over steady net pars. Not bad at all. In fact, in handicapping terms, it's neutral.

 

[D-S]

What is the rationale behind the 1 over net par element of the 2nd 9? Isn’t this very tough for a scratch golfer for example but quite likely for a 36 handicapper?

 

[Colin L]

I don't know the mathematical reason for it, but the scaling up isn't anything to do with what players are likely to do or otherwise ; it's a neutral way of scoring the second 9 such that it will have no effect on your handicap. I guess it was found that this was better achieved by adding on the one stroke but I've no idea how.

 

[D-S]

I don't know the mathematical reason for it, but the scaling up isn't anything to do with what players are likely to do or otherwise ; it's a neutral way of scoring the second 9 such that it will have no effect on your handicap. I guess it was found that this was better achieved by adding on the one stroke but I've no idea how.

Interesting to know why as, even if it has nothing to do with expected play, I would have thought an extra 1 shot on the ‘other’ 9 would surely have more of an effect/influence on a scratch golfers result than a 36 handicapper

 

[jim8flog]

What is the rationale behind the 1 over net par element of the 2nd 9? Isn’t this very tough for a scratch golfer for example but quite likely for a 36 handicapper?

possibly something to with converting the score back to a differential


Score Differential = (113 ÷Slope Rating) x (adjusted gross score –Course Rating – (0.5 x PCC adjustment))