9 hole general play handicap

#81
Voyager EMH

Voyager EMH

Slipper Wearing Plucker of Pheasants
#81
Joined
Mar 14, 2021
Messages
3,223
Location
Leicestershire
Wabinez said:
I used the 9 hole CR

The info:

CR:35.9
HI:3.3
Slope:128
9H Par: 35

Gross score: 39
Click to expand...
9-hole CH = 3 (2.77 rounded)
18-hole CH = 6 (5.54 rounded)
Therefore scaling-up nine hole CH = 3
Scaling-up nine hole score = 35 + 3 + 1 = 39

(39 + 39 - (71.8 - 70)) = 78 - 1.8 = 6.2

and 6.2 x (113/128) = 5.5 (5.47 rounded)

3.3 9-holer scores.jpg
 
#82
W

Wabinez

Journeyman Pro
#82
Joined
Mar 21, 2012
Messages
3,046
stocks4 said:
Glad it worked for you, it should work for all.

Good call out earlier regarding PCC. I just have an extra column for this adjustment in my spreadsheet, and update this if a PCC appears on the app.

I've also worked out how an ESR is handled, but perhaps save that for another day!
Click to expand...
So I have tried on a bigger screen, and I can get the rounded figure of 39, which I need to add to my adjusted gross.

However, if I then use that number and the 'standard' differential calculation....I don't get 5.5!
 
#83
Voyager EMH

Voyager EMH

Slipper Wearing Plucker of Pheasants
#83
Joined
Mar 14, 2021
Messages
3,223
Location
Leicestershire
Wabinez said:
So I have tried on a bigger screen, and I can get the rounded figure of 39, which I need to add to my adjusted gross.

However, if I then use that number and the 'standard' differential calculation....I don't get 5.5!
Click to expand...
Perhaps you need to incorporate the CR-Par bit of the formula for the differential.
 
#86
S

stocks4

New member
#86
Joined
Jul 8, 2022
Messages
12
stocks4 said:
((39+39) - (35.9*2)) * (113/128)
Click to expand...
The above uses your actual 39, your derived 39, the 9H Course Rating and the Slope Rating.

What I find unfathomable is why, despite WHS coming in, we actually use a different interpretation of it to arrive at a course handicap if we play in (say) England vs USA.
The overall effect on Handicap Index is the same but, still, why the difference?!
 
#87
W

Wabinez

Journeyman Pro
#87
Joined
Mar 21, 2012
Messages
3,046
stocks4 said:
((39+39) - (35.9*2)) * (113/128)
Click to expand...
gotcha, that makes sense for my score.

Now, can I throw a curveball in? I have replicated the formula, referencing the right cells etc, but when I adjust the HI (my mate also played 9 holes, scored 38, off HI 1.1) the calculation appears to show a differential of 3.7....but the differential he was calculated on MyEG was 2.8
 
#88
S

stocks4

New member
#88
Joined
Jul 8, 2022
Messages
12
Wabinez said:
gotcha, that makes sense for my score.

Now, can I throw a curveball in? I have replicated the formula, referencing the right cells etc, but when I adjust the HI (my mate also played 9 holes, scored 38, off HI 1.1) the calculation appears to show a differential of 3.7....but the differential he was calculated on MyEG was 2.8
Click to expand...
Yeah, I make that 3.7 too.
I don't suppose he had a PCC adjustment did he? (which I know would be odd, given you didn't).

Another possibility is an ESR adjustment, has he had one SINCE this round?
 
#91
Alan Clifford

Alan Clifford

Active member
#91
Joined
Aug 13, 2020
Messages
244
Since England Golf's recent change, I've implemented the Congu method in my spreadsheet which involves an "18 course handicap based on on 9 holes played". Seems to be working so far.
 
#97
Channel_Buoy

Channel_Buoy

New member
#97
Joined
Mar 16, 2023
Messages
2
Voyager EMH said:
Perhaps a step-by-step worked example might help you and any others who are reading.

Par 35
Course Rating 35.6
Slope Rating 126
Handicap Index 4.9

Here we go

9-hole Course Handicap = (4.9/2) x (126/113) + (35.6 -35) = 3.3 (this will be rounded to 3 for the nine holes played)

18-hole handicap, based on twice round the same 9 is 2 x 3.3 = 6.6 (this is rounded to 7)

This is a scenario where the "scaling-up" nine hole handicap of 4 is one shot more than the nine-holes-played handicap to give a total of 7.
The calculation will give either the same, one shot more or one shot less. Just depends how the figures work out.

In this example the scaling up nine holes (nine net pars plus one shot) is 35 + 4 + 1 = 40.

Lets say our player does his nine holes in two over par 37.

His differential = (37 + 40 -(2 x 35.6)) x ( 113/126) = (77-71.2) x (113/126) = 5.8 x (113/126) = 5.2

I believe this to be correct and accurate.
I don't like it, however.
The player has done nine holes in merely 1.4 shots over the course rating yet is given a differential of 5.2 for doing so.
When your scaling-up nine holes handicap is one more than your nine-holes-played handicap the formula works against you.
Works for you the other way around.
I'm not returning 9-hole scores, because I don't like the formula.

If you are incorporating a formula into a spreadsheet, remember to add scope for PCC.
(Hope I've not done a typo somewhere in the above figures)
Click to expand...
Hello,
Thanks for your contribution to this discussion - I found it very helpful when there's not a lot of clarity out there from the official sites and rule book. One question I have is on the calculations of Course Handicaps. I agree that what you've posted makes sense but I am confused by the fact that when figuring one's CH on a normal 18-hole round one doesn't include CR-Par in the calculation (e.g. if a player with a 15.0 SI plays from the yellow tees on my par-72 course with 134 slope and 70.7 rating his CH as read off the charts at the course would be 18, which corresponds to 15.0x134/133=17.79 rather than 16 if +70.7 - 72 were added to the calculation).

So is there guidance somewhere in the rules that you adjust for course rating less par when making these extrapolation calculations but you don't when just playing the full 18?
 
#99
Channel_Buoy

Channel_Buoy

New member
#99
Joined
Mar 16, 2023
Messages
2
Voyager EMH said:
View attachment 46974 View attachment 46969
Click to expand...
Interesting. I wonder why they wouldn't want you to modify an 18-hole round with CR-Par? Seems like not doing so would adversely affect rounds where players want to play from different tees (and especially affect mixed-gender rounds).

Also I found this discussion paper (https://forums.golfmonthly.com/threads/9-hole-general-play-handicap.112202/) that validates your methodology in all respects except one. Where you advocate calculating the CH (18/9) and CH(9) and subtracting to get the CH(X) (i.e. the CH for the extrapolated 9 holes), the discussion paper says that when CR(18/9) is odd one should always apply the extra one to the holes played by designating those holes as the odd-number handicaps no matter what it happens to say on the card (i.e. CH(9) ≥ CH(X)).

E.g. a player with SI 5.3 plays a course with 9-hole par 35, slope 125 and CR 35.5 on a day with a PCC of +1 plays to 4 over par 39 for the 9-hole round. Under your methodology the player would take a CH of 3 for the 9 holes played (0.5 x 5.3 x 125/113 + 35.5 - 0.5 = 3.4314 ≈ 3) and since the CH(18/9) comes out to 6.8828 ≈ 7 you would add 5 over par 40 to the extrapolated "back-9" for an AGS of 79 which would yield a SD of (79 - 2 x 35.5-1/2) x 113/125 = 6.780.

The discussion paper says you need to apply the 7th stroke of the CH(18/9) to the front 9 played (i.e. the 1st, 3rd, 5th and 7th handicaps if the holes played on the card are marked as odd holes or the 2nd, 4th, 6th and 8th if it's marked as evens) and so the extrapolated portion of the AGS is 35 + 3 + 1 = 39. This gives an overall AGS of 78 which yields a SD of (78 - 2 x 35.5-1/2) x 113/125 = 5.876.

So the Excel formuli should be:
CourseHandicap_18_9 = ROUND(HandicapIndex*Slope_9/113 + 2*(CourseRating_9-Par_9),0)
CourseHandicap_9 = CourseHandicap_18_9 - ROUNDDOWN(CourseHandicap_18_9/2,0)
CourseHandicap_X = CourseHandicap_18_9 - CourseHandicap_9
AGS_X = Par_9 + CourseHandicap_X + 1
AGS_18_9 = AGS_9 + AGS_X
ScoreDifferential_18_9 = (AGS_18_9 - 2*CourseRating_9-PCC/2)*113/Slope_9
 
You must log in or register to reply here.
Top