New USGA 9 Hole Score Differentials Seem Way Off

[iacas]

21 minutes ago, szaino said:

In simple terms a player's GHIN is an average of the differentials for a given number of scores. So why can't it be kept that simple and just be calculated on actual hole played. If you play 9 holes, then just count those holes in the calculation and it would be counted or weighed as 1/2 a round.

 

That's basically what it WAS, and they've shared their reasons why they've moved to this version.

[davep043]

38 minutes ago, szaino said:

The USGA always seems to make things more complicated than they have to be. I am just speaking from many years of playing golf. This thread on GHIN is an example.

 

In simple terms a player's GHIN is an average of the differentials for a given number of scores. So why can't it be kept that simple and just be calculated on actual hole played. If you play 9 holes, then just count those holes in the calculation and it would be counted or weighed as 1/2 a round. 

 

For a 9 hole round, I am not a fan of the new rule which creates a fictitious estimate of what a player would be expected to score on the remaining holes that they never played!! It is an extra step and a superfluous exercise in mental gymnastics.  

Did you take the time to read the explanation for this, and the benefits they believe it will bring?  Do you realize this is another step towards really unifying handicaps world wide?

[Newby]

From another site:

 

The formula for the Expected Score in general is rather complicated and probably therefore it is not published.

But for 9-hole round it is simple:
9-hole Expected Score = (0.52 x Handicap_Index) + 1.2

 

Comments?

[davep043]

57 minutes ago, Newby said:

From another site:

 

The formula for the Expected Score in general is rather complicated and probably therefore it is not published.

But for 9-hole round it is simple:
9-hole Expected Score = (0.52 x Handicap_Index) + 1.2

 

Comments?

Sitting on my sofa and too lazy to do math, this seems fairly close to the numbers I came up with, maybe a tiny bit lower at higher handicap levels.

[Newby]

8 hours ago, davep043 said:

Sitting on my sofa and too lazy to do math, this seems fairly close to the numbers I came up with, maybe a tiny bit lower at higher handicap levels.

That's what I thought

[Imp]

On 4/8/2024 at 5:23 PM, Newby said:

From another site:

 

The formula for the Expected Score in general is rather complicated and probably therefore it is not published.

But for 9-hole round it is simple:
9-hole Expected Score = (0.52 x Handicap_Index) + 1.2

 

Comments?

Do you  know where that calc come from? USGA or someone within it close to the data? The difference between that and the one on the previous page is about .05 for every 10 index. (i.e., 10 index above is 6.4, where the calc on the last page is 6.35) 20 would be 11.6 vs 11.5. Etc... I do like the simpler formula, but agree with dave, the difference would be the higher index (no much) side.

Edited April 10 by Imp

[Chunkitgood]

On 4/3/2024 at 2:31 PM, szaino said:

The USGA always seems to make things more complicated than they have to be. I am just speaking from many years of playing golf. This thread on GHIN is an example.

 

In simple terms a player's GHIN is an average of the differentials for a given number of scores. So why can't it be kept that simple and just be calculated on actual hole played. If you play 9 holes, then just count those holes in the calculation and it would be counted or weighed as 1/2 a round. 

 

For a 9 hole round, I am not a fan of the new rule which creates a fictitious estimate of what a player would be expected to score on the remaining holes that they never played!! It is an extra step and a superfluous exercise in mental gymnastics.  

As I understand it, you don’t have to calculate anything.  They do it for you.

 

You want simple?  Input a bunch of numbers into an app or whatever and get a result.

 

The handicap systems exists to make matches between people at different levels interesting.  It is not a precise measure of how good you are.  I agree probably because of demand from people who think it is they have made the system too elaborate, but it seems pretty simple to use.  You don’t have to understand it.  You really are not obligated to like it.  You can use it if you want, or not, but I personally wouldn’t if real money is at stake.

[nsxguy]

45 minutes ago, Chunkitgood said:

The handicap systems exists to make matches between people at different levels interesting.  It is not a precise measure of how good you are.  I agree probably because of demand from people who think it is they have made the system too elaborate, but it seems pretty simple to use.  You don’t have to understand it.  You really are not obligated to like it.  You can use it if you want, or not, but I personally wouldn’t if real money is at stake

 

"Interesting" ? Interesting choice of words.

 

WHS claims it "enables golfers of different abilities to play and compete on a fair and equal basis, in any format, on any course, anywhere around the world".

 

But you wouldn't use the system if you had "real ca$h" on the line ?

 

So what would you do if you were a "6" and your opponent was a "12" ? Offer him 1 a side ?

 

Or if the 'caps were reversed tell him "I'll take 5 a side" ?

[rogolf]

1 hour ago, Chunkitgood said:

As I understand it, you don’t have to calculate anything.  They do it for you.

 

You want simple?  Input a bunch of numbers into an app or whatever and get a result.

 

The handicap systems exists to make matches between people at different levels interesting.  It is not a precise measure of how good you are.  I agree probably because of demand from people who think it is they have made the system too elaborate, but it seems pretty simple to use.  You don’t have to understand it.  You really are not obligated to like it.  You can use it if you want, or not, but I personally wouldn’t if real money is at stake.

Do you normally play for Monopoly money? 🫤

[Celeras]

I understand the discourse that has already happened, however I will say this: I just got hit with an 8.8 differential after shooting +1 on a local 9, and that doesn't feel particularly good.

[madeinguam81]

2 hours ago, Celeras said:

I understand the discourse that has already happened, however I will say this: I just got hit with an 8.8 differential after shooting +1 on a local 9, and that doesn't feel particularly good.

What’s your index and what was your course handicap? 

[nsxguy]

35 minutes ago, madeinguam81 said:

What’s your index and what was your course handicap? 

 

Please don't confuse him while he's trying to confuse us.

[Shilgy]

3 hours ago, madeinguam81 said:

What’s your index and what was your course handicap? 

At least as importantly…what was the course rating and slope?

[BuckyLasek]

Great thread lads. Two points:

 

1. I need someone to address another point made by larrybud. Sir sandbagger can post much better 9 hole scores and our new system automatically keeps him right where his fake handicap is by assuming the rest of the holes are played to his fake cap. He doesn’t even need to sandbag anymore. 
 

2. Say I’m a 0, I start the season slow, handicap goes up. I’m playing better, shoot 37 on a 37.5 rating, but because my handicap is above 1, I get 1.5 differential. Even though the holes I played were played below the course rating. But I post a few good 18 hole scores and lower my cap and go do that again, suddenly my 37 assumed score would be a lower differential. I shot the same thing on the same course but it was handicapped differently. And sorry usga, playing a few good/bad rounds does not fundamentally change my playing ability. For reasons such as larrybud stated above, I do not understand what the usga is trying to do. I actually think we went backwards with the daily updating a few years ago. Do you think your buddy is a different player based on them having one good/bad day the round prior? That would be insane because our skill level is not changing over night. But the usga is now updating your comparative skill level (shots given) daily and partially basing that off of holes not even played. I think the usga has gone mad. 

Edited June 20 by BuckyLasek

[LayyZeeBoi]

On 3/29/2024 at 6:29 PM, davep043 said:

Your "estimated differential" for 9 holes will be close to half your handicap index + 1.5.  This is something like an average 9 hole score for you, equating to about 3 over par net for 18 holes.  its going my to be just a little less for lower handicappers, a little more for high handicappers.

For you as a 9.0 index, your "average" differential for 18 is going to be something like 3 over par, or about 12.  So posting a diff of 9.6 is significantly better than your average score.  Remember, the average of your best 8 of 20 is going to be lower than the average of all 20.  Go look at your scoring record, how many scores have you posted with a differential less than 9.6?  I bet its no more than 4 of the last 20.

It's a solid explaination, but there's so much guessing going on in this answe.

 

Sorry but OP's point stands.  The new system is f*cked.

[iacas]

3 hours ago, LayyZeeBoi said:

It's a solid explaination, but there's so much guessing going on in this answe.

 

Yep. The organization with millions if not billions of holes of scoring data came up with something that is akin to "guessing."

 

Oy.

[bluedot]

On 4/3/2024 at 3:31 PM, szaino said:

The USGA always seems to make things more complicated than they have to be. I am just speaking from many years of playing golf. This thread on GHIN is an example.

 

In simple terms a player's GHIN is an average of the differentials for a given number of scores. So why can't it be kept that simple and just be calculated on actual hole played. If you play 9 holes, then just count those holes in the calculation and it would be counted or weighed as 1/2 a round. 

 

For a 9 hole round, I am not a fan of the new rule which creates a fictitious estimate of what a player would be expected to score on the remaining holes that they never played!! It is an extra step and a superfluous exercise in mental gymnastics.  

Off the top of my head, I’d guess that the reason that 9 hole scores aren’t counted as “half a score” is that it makes for an apples to oranges comparison between two golfers.

 

If a given golfer mostly (or only) plays 9 hole rounds, his index, consisting of his best 16 half scores would be out of his last 40 total scores, so his index would be based on twice as many outings, which would make changes occur VERY slowly. Alternatively, if the 9 hole golfer’s index was based on only 8 of 20 “half scores”, shouldn’t the 18 hole guy’s index be based on only 4 scores?  I just don’t see a way to make that work.
 

I think it’s important to note that the currently method of posting 9 hole scores is only different in the conversion method to an 18 hole score; 9 hole rounds weren’t posted before.  And while the projected score for the 9 holes not played is counterintuitive, TO ME it’s way, WAY better than the old way.  It bothered the heck out of me to have a 9 hole score combined months later with a second 9 hole score that might have been played in a different season on a different course, and perhaps with different equipment or even a different golf swing.  Algorithmic adjustments might not be perfect, but they’re better than THAT!

 

[nsxguy]

4 hours ago, LayyZeeBoi said:

It's a solid explaination, but there's so much guessing going on in this answe.

 

Sorry but OP's point stands.  The new system is f*cked.

 

Sorry newbie(?) but your opinion is just as invalid as the OP's since you likely have no data-based/statistical way of evaluating the issue.

 

And that would be assuming you had the expertise/training to arrive at a better solution even if you did have the data. 

 

 

[davep043]

5 hours ago, LayyZeeBoi said:

It's a solid explaination, but there's so much guessing going on in this answe.

 

Sorry but OP's point stands.  The new system is f*cked.

Actually, I looked at enough 9-hole posted scores from my home club that there wasn't a lot of guessing involved.  Generally, the Expected differential is between 1.2 and 1.8 strokes higher than half the player's index, lower for lower handicappers, higher for higher handicappers.  Clearly its no "guess" to say that a players overall average of 20 scores will be higher than the average of his best 8 scores, but there IS some estimation as to what the difference is.  And notice, I asked the person to look at his own data to see what those numbers are, asking him for data as opposed to "feelings".  

Again, its easy to say the system is bad, its a lot more difficult to design something better.  The old way of combing 9-hole scores in USGA areas had its problems as well.

[Imp]

On 6/19/2024 at 8:14 PM, BuckyLasek said:

Great thread lads. Two points:

 

1. I need someone to address another point made by larrybud. Sir sandbagger can post much better 9 hole scores and our new system automatically keeps him right where his fake handicap is by assuming the rest of the holes are played to his fake cap. He doesn’t even need to sandbag anymore. 
 

2. Say I’m a 0, I start the season slow, handicap goes up. I’m playing better, shoot 37 on a 37.5 rating, but because my handicap is above 1, I get 1.5 differential. Even though the holes I played were played below the course rating. But I post a few good 18 hole scores and lower my cap and go do that again, suddenly my 37 assumed score would be a lower differential. I shot the same thing on the same course but it was handicapped differently. And sorry usga, playing a few good/bad rounds does not fundamentally change my playing ability. For reasons such as larrybud stated above, I do not understand what the usga is trying to do. I actually think we went backwards with the daily updating a few years ago. Do you think your buddy is a different player based on them having one good/bad day the round prior? That would be insane because our skill level is not changing over night. But the usga is now updating your comparative skill level (shots given) daily and partially basing that off of holes not even played. I think the usga has gone mad. 

Wy are you playing golf and not behind the wheel(s) of your toys? Tell TomD I said Hi. 😉 (If you're the real BL)

 

--kC

Edited June 22 by Imp

[betarhoalphadelta]

22 hours ago, bluedot said:

 

 

It bothered the heck out of me to have a 9 hole score combined months later with a second 9 hole score that might have been played in a different season on a different course, and perhaps with different equipment or even a different golf swing.  Algorithmic adjustments might not be perfect, but they’re better than THAT!

 

 

As I posted in the other active thread on this topic, I understand the confusion. But the very fact that you have this issue at all is that you clearly must play 9-hole rounds very infrequently, if you have to worry about this. And if that's the case, does that very infrequent combination of two 9-hole rounds really impact your index that much? It would likely only be one of your 20 posting rounds, and statistically would also be 60% likely to not be used as one of your 8 of 20 rounds used for your index. 

 

Compare that to someone who plays primarily 9-hole rounds. They're not going to have to combine rounds played from different seasons with different equipment or a different golf swing. Their rounds will be in close proximity (perhaps they might have an outlier of the last round from the last round of a season to the first round of the next season, but that only basically happens for 1 out of 20 like you above). So the very issue that you talk about doesn't really affect the player who regularly plays 9-hole rounds. Most of their rounds will be played in close proximity, with different weather conditions potentially being handled with PCC, and different course difficulty handled by rating/slope, so both are accounted for. 

 

However, the difference lies here: The player who rarely plays 9-hole rounds will have an index that is based on 360 or close to 360 holes of real golf played, in either system. The player who frequently plays 9-hole rounds will have an index based on 360 holes of real golf played in the old system, but will be based on as few as 180 holes of real golf played in the new system, with the difference to get to 360 being imputed scores based on what other similar players might play on similar courses.

 

Which more accurately gives a representation of the player's demonstrated ability, scores based 100% on holes of golf played or scores based on as many as 50% of their holes used for their index not being played?

[Pnwpingi210]

18 minutes ago, betarhoalphadelta said:

 

As I posted in the other active thread on this topic, I understand the confusion. But the very fact that you have this issue at all is that you clearly must play 9-hole rounds very infrequently, if you have to worry about this. And if that's the case, does that very infrequent combination of two 9-hole rounds really impact your index that much? It would likely only be one of your 20 posting rounds, and statistically would also be 60% likely to not be used as one of your 8 of 20 rounds used for your index. 

 

Compare that to someone who plays primarily 9-hole rounds. They're not going to have to combine rounds played from different seasons with different equipment or a different golf swing. Their rounds will be in close proximity (perhaps they might have an outlier of the last round from the last round of a season to the first round of the next season, but that only basically happens for 1 out of 20 like you above). So the very issue that you talk about doesn't really affect the player who regularly plays 9-hole rounds. Most of their rounds will be played in close proximity, with different weather conditions potentially being handled with PCC, and different course difficulty handled by rating/slope, so both are accounted for. 

 

However, the difference lies here: The player who rarely plays 9-hole rounds will have an index that is based on 360 or close to 360 holes of real golf played, in either system. The player who frequently plays 9-hole rounds will have an index based on 360 holes of real golf played in the old system, but will be based on as few as 180 holes of real golf played in the new system, with the difference to get to 360 being imputed scores based on what other similar players might play on similar courses.

 

Which more accurately gives a representation of the player's demonstrated ability, scores based 100% on holes of golf played or scores based on as many as 50% of their holes used for their index not being played?

Depends?

 

is your goal to?

 

accurate measure the ability of a golfer to score over 18 consecutive holes?

 

accurate measure the ability of a golfer to score over 360 holes, regardless of when played or how many were consecutive?

 

accurate measure the ability of a golfer to score over 9 or 18!consecutive holes?

 

im not sure there is a solution that does all those.

 

 

[betarhoalphadelta]

6 minutes ago, Pnwpingi210 said:

Depends?

 

is your goal to?

 

accurate measure the ability of a golfer to score over 18 consecutive holes?

 

accurate measure the ability of a golfer to score over 360 holes, regardless of when played or how many were consecutive?

 

accurate measure the ability of a golfer to score over 9 or 18!consecutive holes?

 

im not sure there is a solution that does all those.

 

 

IMHO the goal of the handicap system is to give a player a measurement of their demonstrated ability in a reasonably accurate way to facilitate level competition between players of disparate skill. 

 

It's a model. As is often said...

 

All models are wrong. Some of them are useful. 

 

Now, maybe there was a serious problem with the old model. I postulated in the other thread that maybe the USGA has data showing a clear trend of players getting back-9 fatigue (or other issues) such that combining 9-hole rounds leads to indexes that are artificially lower than the player's actual demonstrated ability to score over 18 holes. Maybe they have evidence showing the old model to be broken in critical ways for the goal I stated above. 

 

In the absence of such evidence, I'm simply inclined to believe that statistically, larger sample sizes are better than smaller ones for purposes such as determining a player's index. The new USGA model, by definition, cuts the sample size in half for any 9-hole round played. Maybe it's a better model, despite this... But without more detail I struggle to understand how. 

 

[Pnwpingi210]

45 minutes ago, betarhoalphadelta said:

 

IMHO the goal of the handicap system is to give a player a measurement of their demonstrated ability in a reasonably accurate way to facilitate level competition between players of disparate skill. 

 

It's a model. As is often said...

 

All models are wrong. Some of them are useful. 

 

Now, maybe there was a serious problem with the old model. I postulated in the other thread that maybe the USGA has data showing a clear trend of players getting back-9 fatigue (or other issues) such that combining 9-hole rounds leads to indexes that are artificially lower than the player's actual demonstrated ability to score over 18 holes. Maybe they have evidence showing the old model to be broken in critical ways for the goal I stated above. 

 

In the absence of such evidence, I'm simply inclined to believe that statistically, larger sample sizes are better than smaller ones for purposes such as determining a player's index. The new USGA model, by definition, cuts the sample size in half for any 9-hole round played. Maybe it's a better model, despite this... But without more detail I struggle to understand how. 

 

I understand it’s a model.  I was just posing questions the challenge the importance of elements of your post I was responding to.

 

the USGA has data for millions of round of golf.  Both 18 and 9 hole rounds.  

I did the math on my on rounds over the last two years and my 9 hole index ( using the old combine 9 hole round scores to make 18) is lower than my 18 hole index.  I have about 20 9 hole rounds in the calculation and around 90 18 hole rounds.

I can see the value of giving someone a 9 hole index and a 18 hole index.  I think for most golfers they will be different.

 

 

 

 

 

[iacas]

Man, if only the USGA was aware of the fact that they're not counting holes actually played… I wonder if they were aware of this!?!?</sarcasm>

 

Plus y'all seem to forget you could post a score after playing 7 or 14 holes before, or you could post scores where you never hit a cup by picking up and posting your most likely score, right? It's not like the previous method was a PURE measure of the holes you played and finished.

[Pnwpingi210]

1 hour ago, iacas said:

Man, if only the USGA was aware of the fact that they're not counting holes actually played… I wonder if they were aware of this!?!?</sarcasm>

 

Plus y'all seem to forget you could post a score after playing 7 or 14 holes before, or you could post scores where you never hit a cup by picking up and posting your most likely score, right? It's not like the previous method was a PURE measure of the holes you played and finished.

💯agree

[betarhoalphadelta]

3 hours ago, iacas said:

Man, if only the USGA was aware of the fact that they're not counting holes actually played… I wonder if they were aware of this!?!?</sarcasm>

 

Plus y'all seem to forget you could post a score after playing 7 or 14 holes before, or you could post scores where you never hit a cup by picking up and posting your most likely score, right? It's not like the previous method was a PURE measure of the holes you played and finished.

 

Of course. But I would assume that, much like combined 9 hole rounds that are spaced FAR apart, there aren't a lot of players posting 14-hole rounds multiple times a week. I would think that both the combined 9-hole score from months apart and the 14-hole rounds are largely the exception, not the norm. 

 

Whereas the new 9-hole system basically means that every single time you play a 9 hole round, your index is going to be partially based on 9 holes you didn't play. 

 

[iacas]

5 minutes ago, betarhoalphadelta said:

Of course. But I would assume that, much like combined 9 hole rounds that are spaced FAR apart, there aren't a lot of players posting 14-hole rounds multiple times a week.

 

I didn't say it was.

 

Look, I'm not sure what more there is to say about this. Some of y'all don't like it; the USGA (which isn't infallible, but which has billions more data than all this anecdata and made up scenarios) has decided that this is the way to go.

 

What would the next step be? To compare a few hundred golfers who play nine-hole rounds (from seldom to frequently), and evaluate over about the last 22 to 38 scores what their handicaps would be with both methods.

 

My guess is that a 14.2 might become a 14.4 or something. Until someone does that, it's all just conjecture. And we've had a lot of this conjecture.

 

5 minutes ago, betarhoalphadelta said:

I would think that both the combined 9-hole score from months apart and the 14-hole rounds are largely the exception, not the norm.

 

You know who does know…?

 

5 minutes ago, betarhoalphadelta said:

Whereas the new 9-hole system basically means that every single time you play a 9 hole round, your index is going to be partially based on 9 holes you didn't play.

 

We know. We get it.

[DaveLeeNC]

21 hours ago, iacas said:

What would the next step be? To compare a few hundred golfers who play nine-hole rounds (from seldom to frequently), and evaluate over about the last 22 to 38 scores what their handicaps would be with both methods.

 

My guess is that a 14.2 might become a 14.4 or something. Until someone does that, it's all just conjecture. And we've had a lot of this conjecture.

 

I set up a spreadsheet to model this. The 'model golfer' had a 9 hole differential distribution that was Gaussian with a 9 hole mean of 10 and a standard deviation of 2. I further assumed that the front and back 9 scores were independent which seems to be consistent with the USGA assumption since the imputed 9 hole score is independent of the front 9 hole score. This means that the differentials that this golfer shoots over 18 will have 95% of them lie in the range of 14.5 and 25.5. 

 

So I just let this golfer 'play' his 18 hole rounds and calculated his index on both an 18 hole basis and just used the front 9 scores to calculate a different index for only 9 hole scores. His/her 18 hole index ended up around 16.7 and his/her 9 hole index ended up around 19.5. 

 

If the front and 9 hole scores have correlation then this spread will get worse. It would get smaller if there was (not modeled) negative correlation (which seems unlikely to me). It would also get smaller for the case of a golfer who legitimately plays worse on the back side (most likely due to fatigue). I would hardly call this the norm but it certainly happens. Of course there are also players like me who almost always putt better on the back side vs. the front (as I finally figure out the speed). 

 

This is not some small thing for 9 hole golfers. 

 

dave

 

ps. The imputed 9 hole diff was Index/2 + 1.5 

Edited June 23 by DaveLeeNC

[Pnwpingi210]

10 minutes ago, DaveLeeNC said:

 

I set up a spreadsheet to model this. The 'model golfer' had a 9 hole differential distribution that was Gaussian with a 9 hole mean of 10 and a standard deviation of 2. I further assumed that the front and back 9 scores were independent which seems to be consistent with the USGA assumption since the imputed 9 hole score is independent of the front 9 hole score. This means that the differentials that this golfer shoots over 18 will have 95% of them lie in the range of 14.5 and 25.5. 

 

So I just let this golfer 'play' his 18 hole rounds and calculated his index on both an 18 hole basis and just used the front 9 scores to calculate a different index for only 9 hole scores. His/her 18 hole index ended up around 16.7 and his/her 9 hole index ended up around 19.5. 

 

If the front and 9 hole scores have correlation then this spread will get worse. It would get smaller if there was (not modeled) negative correlation (which seems unlikely to me). It would also get smaller for the case of a golfer who legitimately plays worse on the back side (most likely due to fatigue). I would hardly call this the norm but it certainly happens. Of course there are also players like me who almost always putt better on the back side vs. the front (as I finally figure out the speed). 

 

This is not some small thing for 9 hole golfers. 

 

dave

I like this idea of modeling.

 

were the scores you input actual scores for a real golfer?