Not a fan of GHIN new 9 hole scoring system

[Oswinner]

I replied in another thread about this but this thread is more up-to-date…

 

 

I played my first 9-hole round the other day and seeing as I keep my own HCP index atm as I’ve had two years off being a member of a golf course (cost cutting buying a house and having a baby) I decided to try and work this bleeder out.

 

I found via searching the web that the ‘secret formula’ for expected score is )

(0.52*HCP)+1.2

 

I then wondered how my handicap would look like if I split my last 20 18-hole rounds into 40 9-hole rounds with the 2024 way of calculating. I then took the average of the best 16 out of 40 rounds.

 

The answer? The 18-hole handicap (average of best 8 out of 20) was EXACTLY the same as the 9-hole handicap (average of best 16 out of 40).

 

So I guess the new system is working if you think about it…?

Edited July 9, 2024 by Oswinner

[Newby]

10 hours ago, Oswinner said:

 

I found via searching the web that the ‘secret formula’ for expected score is )

(0.52*HCP)+1.2

 

Where did you find this? It seems that no one else has.

How does that work If the 'secret formula' system does it hole by hole (as the book suggests). 

[haleew02]

I ran the secret formula calculation on the 7 9 hole scores I have posted so far this year across different courses/tees and it ties perfectly to the differentials generated.  Thanks Oswinner for the info.

[Oswinner]

16 hours ago, haleew02 said:

I ran the secret formula calculation on the 7 9 hole scores I have posted so far this year across different courses/tees and it ties perfectly to the differentials generated.  Thanks Oswinner for the info.

No problem.

 

and I cannot fully remember where I read it. Interesting why they haven’t fully clarified the formula. Maybe they don’t want it to sound too complicated? Or maybe they have plans to further tweak it later on?

[Schulzmc]

I rarely play 9, but yesterday a number of factors (paired up with some really bad golfers, rain on the horizon, Cub game beginning on the big TV by the bar) convinced me to quit after the ninth hole. Shot 45 on the front. Two weeks ago I shot 90 on the same course and earned a 17.1 differential. But this nine hole score got a 16.4 when they applied the expected score. Apparently they assumed I would play better on the back nine. Based on my past, that is likely the case (I’m a 12 index). 

 

Surprisingly, the formula seems to have worked. 

[haleew02]

I think we can all agree that for the golfer that rarely plays 9 holes or posts a bad 9 hole score, the new methodology is fine as it will almost definitely not be included in the best 8 of last 20.  
 

The issue that many have raised here is that the new calculation makes it extremely difficult to actually lower your handicap by posting 9 hole scores as you would need to consistently shoot 2 below your course handicap just to maintain your index.  This along with up to half of your handicap being calculated using holes that weren’t even played is a bit frustrating.

 

i did receive an email back from the USGA to at least record my feedback.  While the reasons provided for the change were the same as all of the marketing materials that were provided at the beginning of the season there was a clarification that the differential calculation for 9 hole scores has nothing to do with the difficulty of the holes not played and is solely based on the golfers index at the time of posting.  This gives me more faith in the secret formula that Oswinner posted earlier in this thread.

 

Obviously, nothing is going to change with this in the near future but it is nice to come on here and see that there are other 9 hole golfers out there that have similar experiences and are also frustrated by it.  Sometimes it just nice to not feel alone.

[Newby]

On 4/19/2024 at 10:35 PM, rogolf said:

The "course slope of standard difficulty"?  Is this a slope of 113?  And that seems to be only part of it, doesn't there also need to be a course rating for the nine holes not played?  A "differential" infers that it is calculated from two things, in this case wouldn't it be the expected score and a course rating?

Further, here is what the USGA says on its website, (my bolding)

"The expected score is based on the average Score Differential of a player with a given Handicap Index and a normal distribution of scores – so it is not specific to each player."

The England Golf expresses slightly differently.

The expected score is based on the player's Handicap Index over a course of standard difficulty.

and adds

A player with a Handicap Index of 10.0 will have a lower expected score than a player with a Handicap Index of 15.0.

 

'Standard difficulty' is a slope of 113

 

[Newby]

On 7/9/2024 at 9:36 PM, Oswinner said:

I found via searching the web that the ‘secret formula’ for expected score is )

(0.52*HCP)+1.2

 

 

When you say HCP do you mean Course Handicap (CH) or Handicap Index (HI)?

[haleew02]

43 minutes ago, Newby said:

When you say HCP do you mean Course Handicap (CH) or Handicap Index (HI)?

Handicap Index

[Newby]

2 hours ago, haleew02 said:

Handicap Index

So a 20.0 HI would produce an answer of (0.52 * 20.0) + 1.2 = 11.6

Is that the 'expected score' or what?

[DaveLeeNC]

21 minutes ago, Newby said:

So a 20.0 HI would produce an answer of (0.52 * 20.0) + 1.2 = 11.6

Is that the 'expected score' or what?

That would be the "expected differential" that will be applied to your unplayed 9 holes to generate an 18 hole differential from a 9 hole round.

 

dave

[Newby]

18 minutes ago, DaveLeeNC said:

That would be the "expected differential" that will be applied to your unplayed 9 holes to generate an 18 hole differential from a 9 hole round.

 

dave

I had understood that on or other authorities had said the same algorithm was used for all missing holes whether it be 3 or 9.  How would that work if I haven't been given duff information?

[DaveLeeNC]

1 minute ago, Newby said:

I had understood that on or other authorities had said the same algorithm was used for all missing holes whether it be 3 or 9.  How would that work if I haven't been given duff information?

 

As I understand it the expected differential (by hole) is applied to each unplayed hole. So I assume that when you do that 9 times (for a given side) you get same result as the referenced formula. 

 

dave

[Newby]

7 minutes ago, DaveLeeNC said:

 

As I understand it the expected differential (by hole) is applied to each unplayed hole. So I assume that when you do that 9 times (for a given side) you get same result as the referenced formula. 

 

dave

I've just found in a note from England Golf relating to all CONGU authorities

 

The Holes Not Played adjustment is only relevant for 18-hole rounds. For a 9-hole round to be acceptable for handicapping in GB&I all 9 holes must be played and a Net Double Bogey adjustment would be applied to any holes started but not completed.

[DaveLeeNC]

6 minutes ago, Newby said:

I've just found in a note from England Golf relating to all CONGU authorities

 

The Holes Not Played adjustment is only relevant for 18-hole rounds. For a 9-hole round to be acceptable for handicapping in GB&I all 9 holes must be played and a Net Double Bogey adjustment would be applied to any holes started but not completed.

Same is true under the USGA.  dave

[DaveLeeNC]

1 hour ago, Newby said:

I've just found in a note from England Golf relating to all CONGU authorities

 

The Holes Not Played adjustment is only relevant for 18-hole rounds. For a 9-hole round to be acceptable for handicapping in GB&I all 9 holes must be played and a Net Double Bogey adjustment would be applied to any holes started but not completed.

 

I typed before I engaged my mind here. While the 9 vs. 18 hole requirement appears to be the same (USGA vs. CONGU), a hole started but not completed is different. Under USGA rules we use most likely score for holes started by not completed (NDB limited) - Rule 3.3. 

 

dave

[Newby]

9 hours ago, DaveLeeNC said:

 

I typed before I engaged my mind here. While the 9 vs. 18 hole requirement appears to be the same (USGA vs. CONGU), a hole started but not completed is different. Under USGA rules we use most likely score for holes started by not completed (NDB limited) - Rule 3.3. 

 

dave

Yes. I had noticed that before. We just enter (an appropriate code depending on front end software supplier) for 'Did Not Start' or 'Did Not Finish' and the software takes care of the transmission to central WHS.

Edited July 12, 2024 by Newby

[Imp]

On 7/9/2024 at 4:36 PM, Oswinner said:

(0.52*HCP)+1.2

So take "barely over half your HI" and add 1.2. Yep. Need to shoot ~2 under 1/2 your index to just maintain, or else it's going to go up. 3 under or more on just 9 holes to go down a smidge. If you can't get 2 under, it's going up.

 

If you shoot double that on 18 holes (6 under HI), you're approaching exceptional score territory with a decently lower differential as a reward, but they expect you to be able to do that in 9 to have any effect. 

 

Summed up:

Need around ~3 under 1/2 HI on 9 to have a lower differential.

Need only 1 under full HI on 18 to have a lower differential. 

 

Again, not a fan. 

Edited July 15, 2024 by Imp

[dekez]

17 minutes ago, Imp said:

So take "barely over half your HI" and add 1.2. Yep. Need to shoot ~2 under 1/2 your index to just maintain, or else it's going to go up. 3 under or more on just 9 holes to go down a smidge. If you can't get 2 under, it's going up.

 

If you shoot double that on 18 holes (6 under HI), you're approaching exceptional score territory with a decently lower differential as a reward, but they expect you to be able to do that in 9 to have any effect. 

 

Summed up:

Need around ~3 under 1/2 HI on 9 to have a lower differential.

Need only 1 under full HI on 18 to have a lower differential. 

 

Again, not a fan. 

I've noted the same. I dont understand the rationale, so have resorted to combining two 9 hole scores the old way.

[sui generis]

9 minutes ago, dekez said:

I've noted the same. I dont understand the rationale, so have resorted to combining two 9 hole scores the old way.

 

Why bother when you could just invent any old numbers that'd impress your own ego and post that? 

[Newby]

12 minutes ago, dekez said:

I've noted the same. I dont understand the rationale, so have resorted to combining two 9 hole scores the old way.

Cheating really 😮

[haleew02]

Isn’t this reverse cheating actually as it would only make it harder to win in a handicapped/net match or tournament?

 

As there will always be people that try to use the rules to their advantage, this seems like a very easy way for someone to legally sandbag.  All you would have to do is post 9 hole scores equal to your course handicap and your handicap would go up quickly if there are some good 18 hole rounds that would then drop off.  Then, when you shoot an 18 score that is just double your 9 hole ones, it wouldn’t be suspicious but would post as a much lower differential 

[dekez]

1 hour ago, Newby said:

Cheating really 😮

Exactly! The ole' american way...

[dekez]

1 hour ago, sui generis said:

 

Why bother when you could just invent any old numbers that'd impress your own ego and post that? 

 

It's not that. After all you are better off with an artificially high handicap than an artificially low one.  What is the rationale for adding 1.2 to your handicap on the second 9?  Are there statistics that prove out that folks shoot worse on the back 9?

[iacas]

2 hours ago, Imp said:

Need around ~3 under 1/2 HI on 9 to have a lower differential.

Need only 1 under full HI on 18 to have a lower differential. 

 

16 index.

6 + 16 * 0.52 + 1.2 = 15.5 differential

 

I mean, it's not like the USGA didn't have 300+ million rounds to try this on from 2020-2023… Oh, wait, they did? And they went forward with it anyway? They must have decided that it was a good change.

 

2 hours ago, dekez said:

I've noted the same. I dont understand the rationale, so have resorted to combining two 9 hole scores the old way.

 

Like others said, you're cheating. And if you ascribe negative connotations to that — because you're "lowering" your index and not raising it — then you're intentionally breaching the Rules of Handicapping.

 

You're breaking the rules.

 

This from a friend was funny to me. Shoots 37 (par 36), rating/slope are 35.4/139… GHIN shows his differential as 999. 😄 "Man, the new nine-hole thing really inflates your index! He got a 999!" 😄 

 

 

(He doesn't have an established index yet, and this is his first nine holes. It'll calculate a differential when he gets to 54 holes.)

[DaveLeeNC]

1 hour ago, dekez said:

 

It's not that. After all you are better off with an artificially high handicap than an artificially low one.  What is the rationale for adding 1.2 to your handicap on the second 9?  Are there statistics that prove out that folks shoot worse on the back 9?

 

What they say that they have done is to use the expected differential for the unplayed 9 holes. This is what they said that they did and it looks to be consistent with other data that I have seen regarding how players shoot on average vs. index. The 'upward bias' occurs because your index is not built from 'expected differentials' but from the best 8 of 20 of your actual differentials. In pretty much every case that I can imagine your average (expected) differentials of the scores that make up your index will be lower than your average differentials. 

 

To be fair to the RB's this is a difficult problem if you feel that you must generate an 18 hole differential using only a single 9 hole differential data point - at least in the context of calculating a handicap index. 

 

dave

[Pnwpingi210]

6 hours ago, dekez said:

 

It's not that. After all you are better off with an artificially high handicap than an artificially low one.  What is the rationale for adding 1.2 to your handicap on the second 9?  Are there statistics that prove out that folks shoot worse on the back 9?

Not that they have shared.

 

But the USGA found that many 9 hole rounds were being combined for a post-able 18 hole round score lower than any of that golfers 18 hole round score.  To summarize the old method was producing 9 hole + 9 hole round scores that a golfer unable to shoot for a full 18 hole round.  It was common enough they changed the rule. 

[Newby]

1 hour ago, Pnwpingi210 said:

Not that they have shared.

 

But the USGA found that many 9 hole rounds were being combined for a post-able 18 hole round score lower than any of that golfers 18 hole round score.  To summarize the old method was producing 9 hole + 9 hole round scores that a golfer unable to shoot for a full 18 hole round.  It was common enough they changed the rule. 

Where was this published?

[Pnwpingi210]

5 minutes ago, Newby said:

Where was this published?

https://www.usga.org/content/dam/usga/pdf/2024-revision/Detailed-Infographic-2024-9-hole-scores.pdf
 

see bottom bullet points

[betarhoalphadelta]

1 hour ago, Pnwpingi210 said:

https://www.usga.org/content/dam/usga/pdf/2024-revision/Detailed-Infographic-2024-9-hole-scores.pdf
 

see bottom bullet points

I personally would love to know the actual data behind this. (I'm an engineer, so wanting to see data before forming opinions is a dangerous character fault of mine.)

 

I.e., they say it was "common" that the combined score was a lower differential than any other score in a player's scoring record. 

 

How common is "common"? By simple logic, it should be expected to occur 5% (1 out of every 20) of the time. Because one of your rounds must be your lowest differential, so unless there is some advantage to combining 9-hole rounds, it should be expected to happen that often. 

 

Then there's the exceptional score chart. I'd love to see the data whether combined 9-hole rounds that would result in "exceptional" scores occurred more frequently than the odds for 18-hole rounds would suggest. 

 

If the data shows that players were posting 9-hole combined rounds that were their lowest differential >5% of the time, or if they were posting exceptional scores at a higher rate than the 18-hole round odds would suggest, that makes sense. 

 

But "it was also common" doesn't give us that.