GHIN 9-Hole Differential
I'm curious what this is going to do to weeknight 9 hole leagues. I know one of the ones I was considering joining does its scoring through the GHIN app so the option to wait to post wouldn't be available. I imagine this could be a common situation.
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I tried to be polite.
At the club we use Golf Genius for some events and it will post to GHIN. There is a Thursday night 9 hole 2 man which gets posted automatically through Golf Genius. So, I guess we are going to find out. I know some people are going to be WTF!
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The uncensored workaround was a fantastic touch
JohnnyO3478
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I was being facetious with the apology. I apologize for not being more clear.
Seriously, though it's a little refreshing to see that at least one more person is willing to contribute a little data to the effort! Please let me know how you feel about it after recording a 9-hole round or two.
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A lot of the guys In the mens league at my course get frustrated because it’s only 9 holes, and it’s played from the combo tees (a bit up for many of their regular distances) which means on any given week they can go all scorched earth on a 9.
Wondering how much of an impact this will have to that.
JohnnyO3478
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Open mind. Nice. Let us know how it works out.
I don’t care enough about my handicap to care lol. I only have kept it up bc it comes with the club membership. If I was in any tournaments or matches at the club that used it I’d probably care a bit more.
JohnnyO3478
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JohnnyO3478
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Two tales of two nines. Collected a little more data this weekend with 18 hole rounds on Saturday and Sunday. One was a classic high index player contrasting nines round of 40 on the front and 50 on the back. The next was a more even keeled round that is not unheard of for a high index guy to post of 42/43. If you look at 6 recent rounds - 3 nine hole and 3 eighteen hole, I am not seeing a whole lot of reason to be angry about how the GHIN system is handling 9 hole rounds this year.
Nines - Score (Differential)
42 (19.0)
37 (14.7)
40 (17.9)
Eighteens - Score (Differential)
85 - 43/42 (16.2)
90 - 40/50 (21.0)
89 - 42/47 (20.0)
Two of my nine hole scores are right in line with any given 9 that I will card in an 18 hole round and the asssigned differentials for those seem to be in the ball park. One of my nine hole scores is a serious outlier - and the system seems to recognize that and doesn't go crazy low on the differntial.
During this period - my index has been descending through the 19s and 18s. I happen to be playing my best golf, as I have finally found an instructor that I relate to really well. My point is that my game is not in a steady state at the current moment. People on a plateau, game-wise may have a different experience.
I'd still encourage folks to give the new system a whirl - for data's sake, if nothing else. Combining 9s on your own will not tell us anything.
Nines - Score (Differential)
42 (19.0)
37 (14.7)
40 (17.9)
Eighteens - Score (Differential)
85 - 43/42 (16.2)
90 - 40/50 (21.0)
89 - 42/47 (20.0)
Two of my nine hole scores are right in line with any given 9 that I will card in an 18 hole round and the asssigned differentials for those seem to be in the ball park. One of my nine hole scores is a serious outlier - and the system seems to recognize that and doesn't go crazy low on the differntial.
During this period - my index has been descending through the 19s and 18s. I happen to be playing my best golf, as I have finally found an instructor that I relate to really well. My point is that my game is not in a steady state at the current moment. People on a plateau, game-wise may have a different experience.
I'd still encourage folks to give the new system a whirl - for data's sake, if nothing else. Combining 9s on your own will not tell us anything.
JohnnyO3478
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Ultimate Hacker tale of 2 nines ....
JohnnyO3478
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I ended my round on Saturday after playing only 12 holes - due to rain. This was my first input into the system for a greater than nine but less than 18 round. I'd carded 43 on the front and was 2 over on the back after 3. Looks like the system assumed I'd finish the back with a 45 or so. Again - not unreasonable for a guy with my index.
Curious - all you folks who plan to combine your own 9s before submitting a score instead of just submitting each 9 individually - will you enter a score for 10-17 holes played?
Curious - all you folks who plan to combine your own 9s before submitting a score instead of just submitting each 9 individually - will you enter a score for 10-17 holes played?
In RI, the season does not start until April 1 and my Friday evening 9-hole league starts at the end of April, so I'll be posting 9-hole scores weekly. I'll report back when I start seeing results.
In the past, I've combined 9-hole rounds myself (we play alternating front/back 9s) by waiting to post. However last season, I posted 9s right away had a few 9s from my home course combined with a 9 I played at a completely different course. It works mathematically because of the rating/slope system but it always struck me as an odd thing to do. Frankly, I don't think the new system is any worse.
In the past, I've combined 9-hole rounds myself (we play alternating front/back 9s) by waiting to post. However last season, I posted 9s right away had a few 9s from my home course combined with a 9 I played at a completely different course. It works mathematically because of the rating/slope system but it always struck me as an odd thing to do. Frankly, I don't think the new system is any worse.
JohnnyO3478
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I am tending to agree that there's nothing noticably wrong with the new way GHIN handles incomplete rounds.
Another good argument for posting rounds as soon as they are complete as it will contribute to the accuracy of any playing conditions calculation that may be applied.
greenOak
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The USGA has proven time after time that they don't understand basic statistics.
Combining consecutive 9-hole scores gives the same distribution of scoring as playing 18-hole rounds (assuming you play to the same level in both the front and back 9 which probably isn't true for most players but is a reasonable assumption since some will tend to be a bit better on the front while others will tend to be a bit better on the back). The new system results in less variance in entered scores which will mess up handicap calculations.
Quote from the USGA itself
Combining consecutive 9-hole scores gives the same distribution of scoring as playing 18-hole rounds (assuming you play to the same level in both the front and back 9 which probably isn't true for most players but is a reasonable assumption since some will tend to be a bit better on the front while others will tend to be a bit better on the back). The new system results in less variance in entered scores which will mess up handicap calculations.
Quote from the USGA itself
- Combining two independent 9-hole scores often resulted in more volatility and was highly dependent on the order in which scores are combined.
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JohnnyO3478
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In case that comment was directed at me - and in the interest of keeping the conversation going - I will bite.
Please explain the math to us morons that produces the same amount of volatility for independent 9 hole rounds vs complete 18 hole rounds under the following conditions:
1. 9 hole Round 1 played in nasty weather on a day where less than 8 people recored a round plus 9-hole Round two played on a day that has perfect conditions, ideal for scoring vs an 18 hole round completed in ideal weather conditions.
and
2. 9-hole Round 1 being played by a player in perfect health (feeling really good that day) plus 9-hole Round two played by the same player who is under the weather or recovering from an injury vs an 18-hole round played by that same player in perfect health (feeling really good that day).
Neither of those two situations seem all that far fetched.
I take it from your passion on the subject that you have recorded a few 9 hole scores this year and they did not produce the differential result you'd expect?
I've had the opposite reaction. So far I've recorded 7 9-hole scores and one 12-hole score - and the differentials that the system spat out all seem reasonable to me. I'm a high index player - so I'm seeing results that often are representative on what you'd see with a tale of 2 nines kinda round. I looked at the 9 hole rounds that a low index player friend of mine is posting and it seems like the system is more or less doubling his 9s to produce a differential. That makes sense as he's more likely to be more consistent.
I'm new to the game and I admit I have no idea just how badly the USGA has hurt some of folks in the past - but all signs so far seem to be that they are on the right track here. No dog in the hunt. I am sure that given time - they will wound me too ....
All I am suggesting is - give it a chance. Record some scores. Create data. I hear that folks who are super good at math LOOOOOOVE data.
greenOak
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1. My post was not aimed at any poster - it's just me ranting about the USGA
2. I have not played a round of golf in 2024 outside of simulator, nor do I play very many 9 hole rounds in general. I also don't play handicapped events so this change is hardly going to have any effect on me.
3. Bad math being passed off as legit pisses me off - a lot.
As for your examples, it is true there are many variables that can affect the accuracy of the handicap system, but I do not see why the new system should be any better than the old system at dealing with such cases. Another thing you seem to be confused about is that the variance from one nine to another is irrelevant - all that matters is the variance of the scores (technically differentials) that you actually post. For example, in your examples, under the old system we should actually expect to see less volatility in the combined scores posted for handicap purposes because the fact that you play one nine in very favorable conditions, and one round in very unfavorable conditions makes it more likely that you're combined score will be closer to your average than if you get to (or have to) play all 18 holes in favorable or unfavorable conditions.
The simplest mathematical model (where scoring on every hole is independent of one another) suggests that entered scores under the new system will have less variance than scores entered from playing 18 holes. If you insist, I can lay that argument out rigorously, but the intuitive reason is because there is no variance in the "expected differential for 9 holes" that gets added to your nine hole differential.
I would love to see data on this, but unfortunately the USGA has provided none. Like I said earlier I have very few 9-hole rounds personally logged, but if someone (or somebodies) have a large dataset of 9-hole rounds with the corresponding course rating / slopes I'd be glad to analyze it.
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Someone explain this to me like I'm a five year old...
Sunday I go 40/40 for an 80 and an 8.9 differential. Wednesday, on the same course from the same tees, I shoot 40(again) on the back and USGA makes it a 10.7 differential.
Sunday I go 40/40 for an 80 and an 8.9 differential. Wednesday, on the same course from the same tees, I shoot 40(again) on the back and USGA makes it a 10.7 differential.
JohnnyO3478
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What is your index?
The system assumes that you will finish your round on the average of how all the people in the system with your index would finish the round. Looks like they think that on average, a person with your index will have a back nine slightly worse than your front nine.
I'm gonna guess your index is around 8-10. Am I correct?
The system assumes that you will finish your round on the average of how all the people in the system with your index would finish the round. Looks like they think that on average, a person with your index will have a back nine slightly worse than your front nine.
I'm gonna guess your index is around 8-10. Am I correct?
Can't explain at a 5 year old level because even a 5 year old wouldn't buy a made up score being legitimate.
Only reason I can come up with for those differentials varying by nearly 2 strokes is Unconfirmed Stroke Guesstimate Applied.
I used to think that simulator play was make-believe golf. No, this new 9-hole scoring is. It's AI golf, and it's stupid. I don't care about any supposed mathematical accuracy as to ability or elements on any given day. Did club contact ball? No. So why is a score that never happened in real life applied to my GHIN?
So, so dumb.
So, so dumb.
9.9, course handicap on the back is 5. Front which I didn't play is 4.
JohnnyO3478
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Sounds about what I've seen so far. The closer you get to scratch, the closer the system seems to go towards doubling the one nine. I'm a 17.3 index. I'm getting results that would be equivalent to 40 45 for a 9 hole score of 40. You are getting more like 40 42 for a 9 hole score.
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greenOak
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The new system adds what it deems to be your expected score for 9 holes to calculate the differential. 40 on a 34.9/132 rated course comes out to roughly a 4.4 differential, then it adds what it thinks your expected differential should be which in your case is about 6.3. When you shot 40-40, you played better than expected on the second nine which is why that differential is lower.
Your course handicap (4 vs 5) is irrelevant for this calculation.