• Discover new ways to elevate your game with the updated DGCourseReview app!
    It's entirely free and enhanced with features shaped by user feedback to ensure your best experience on the course. (App Store or Google Play)

Round Ratings

You are right - that is all it is. Not sure how timg implements this, but using that method would save a few machine computational cycles.

However, I do like an equation that is easy to explain in the 1) driving, 2) putting and 3) "extreme length" components.

With that freed up computational horsepower on his server, he could implement an if/then and make sure SSE is never below 2 throws per hole.....maybe even 2.1 throws per hole.
 
Last edited:
Ok, *if* I'm going to go to a bunch of work redesigning the SSE formulas, this time around I at least a larger pool of data. So.. I'm hoping to collect SSA data *and* course layout lengths for some more rounds/events, hopefully this time including some non-18-hole courses. I'd also need to know which of the lightly wooded, moderately wooded, and heavily wooded descriptors would best-fit the rounds. If anyone happens to have any data on this topic, I'd love to acquire it. You can PM it to me. ;)
 
You are right - that is all it is. Not sure how timg implements this, but using that method would save a few machine computational cycles.

However, I do like an equation that is easy to explain in the 1) driving, 2) putting and 3) "extreme length" components.

With that freed up computational horsepower on his server, he could implement an if/then and make sure SSE is never below 2 throws per hole.....maybe even 2.1 throws per hole.

I'm questioning whether the extreme length component is real, or just a correction to the putting component.
 
I'm questioning whether the extreme length component is real, or just a correction to the putting component.

From some preliminary data, I'm showing the per-hole (b) component of the slope formula (y=mx+b) somewhere down around 1.3 (instead of the 1.67 we've been using), but I need a ton more data (especially data from non-18-hole courses) to better quantify that. :p
 
1) ^ Gentlemen, thinks for all your computational juggling to refine this.
2) I bet this feature helps people earn "workout" achievements as it will encourage us to enter rounds in our scorebook.
 
Probably this was covered - my apologies for not wading through the 19 pages of replies.

But, how does all of this work for courses with multiple pin positions?

Presumably it's straightforward for red vs. white vs. blue vs. yellow.

But, my home course (Rogers Lakewood) has multiple pin positions for most every hole, and a couple of holes with two tees. So, a lot more than four possible combinations - and we probably play through more than four in a year.

If I enter in a round, and select the "blue" tees, I guess it uses whatever layout's currently entered in for blue?

What if someone comes along and changes the definition of blue later? Are my previously entered rounds affected? Or are their ratings left alone, and it's only newly entered rounds that will use the "new" definition of blue?

Does the date I enter for my round matter?

How should this work out with ratings? It's just up to you, when you enter your round, to make sure that the correct pins are entered?

I'll be tempted to explore another issue when the snow starts to fall. Since rating are only calculated for complete rounds, and this course switches from 24 to 21/22 in the winter, I'll be tempted to make a new target for scorebook entries. The way things are handled currently, that may have to be a whole new course? Rogers Lakewood Winter, or some such?
 
But, how does all of this work for courses with multiple pin positions?

Presumably it's straightforward for red vs. white vs. blue vs. yellow.

But, my home course (Rogers Lakewood) has multiple pin positions for most every hole, and a couple of holes with two tees. So, a lot more than four possible combinations - and we probably play through more than four in a year.

If I enter in a round, and select the "blue" tees, I guess it uses whatever layout's currently entered in for blue?

What if someone comes along and changes the definition of blue later? Are my previously entered rounds affected? Or are their ratings left alone, and it's only newly entered rounds that will use the "new" definition of blue?

When you enter a scorecard round, and pick a 'tee' color, the fields populate based on the current pin positions and hole lengths on the 'hole info' tab for that course. Previous rounds, thus, are not affected by changes to the course hole info tab. You will want to make sure, though, that the course page gets updated properly whenever the course layout changes (and before you enter a round in your scorebook).

For courses with more than four pin positions, there isn't a great method of dealing with that. Mostly users seem to use the 'B' position slot and actually change the hole lengths for each pin position. You can see that in use, for example, on this course page:

http://www.dgcoursereview.com/course.php?id=6105&mode=ci
 
OK - thanks. That makes sense, and seems like a reasonable way to handle it.

If someone doesn't check their pin positions when they enter a round, if it's a recent round, hopefully the default's OK. If it's a long-ago round, well, that might add some noise to the system.

It looks like the hole-by-hole elevation indications don't enter the SSE, and so don't touch the round ratings?

But that the amount of trees _does_ matter? And that's just the overall course description, like " Mostly Flat & Lightly Wooded" and doesn't enter on a hole-by-hole basis?
 
OK - thanks. That makes sense, and seems like a reasonable way to handle it.

If someone doesn't check their pin positions when they enter a round, if it's a recent round, hopefully the default's OK. If it's a long-ago round, well, that might add some noise to the system.

It looks like the hole-by-hole elevation indications don't enter the SSE, and so don't touch the round ratings?

But that the amount of trees _does_ matter? And that's just the overall course description, like " Mostly Flat & Lightly Wooded" and doesn't enter on a hole-by-hole basis?

Hi Agibson,

Yes indeed, the only inputs into the SSE formulas are overall layout length (the sum of every hole length) and the 'foliage value'. There's been a lot of past discussion as to the relative merits/limitations of using course 'foliage' density as an approximation of course technicality/riskiness, and it definitely does pose some accuracy problems. However anything else would require new database fields for every single course page (i.e. programming work for timg, and then individual DGCR users would need to change/update the new field(s)). You can find the most recent discussion on this topic over on the 'DGCR Suggestions' section of the forum, if you're interested. :)
 
From some preliminary data, I'm showing the per-hole (b) component of the slope formula (y=mx+b) somewhere down around 1.3 (instead of the 1.67 we've been using), but I need a ton more data (especially data from non-18-hole courses) to better quantify that. :p

If you come up with a linear formula (or 3) for score per hole, based on average hole length and foliage, I don't see how number of holes would need any further adjustment when developing the formula. Any number of holes should work the same.

I think this would work about as well as any course-wide adjustments for weird lengths or strange numbers of holes.

It seems you could test that with the same data you've used so far, as you'd only be setting 6 parameters.
 
Sorry if this was mentioned before, but I don't feel like combing through this entire thread...

Could a "Rating" option be added for the "Sort" menu? I'd love to be able to sort my rounds by rating to view them, instead of just course, date, and score.

Just throwing this out there!
 
And, one more in the series of, "I don't want to read the whole thread carefully."

It sounds like the formula may just not make much sense for very short holes, or for courses with few holes? And maybe for different reasons?

For courses with few holes, is it just because each throw ends up making a huge contribution to the reading? So a one throw difference could be 30 points?

For short courses, is it just that formula pushes it so that you have to birdie everything to get a decent round, or in the extreme case so that you even need to ace a couple of holes?
 
For courses with few holes, is it just because each throw ends up making a huge contribution to the reading? So a one throw difference could be 30 points?

For short courses, is it just that formula pushes it so that you have to birdie everything to get a decent round, or in the extreme case so that you even need to ace a couple of holes?

Hi Agibson,

For rating vs. number of holes, yes, you've got it. It's the stepwise problem. A single missed putt on a 9-hole course is the mathematical equivalent of two missed putts over 18 holes, thus the rating-points-per-throw interval is double. :p i.e. you get big gaps in round ratings between each throw the smaller the number of holes in the layout. That's one of the reasons why the PDGA doesn't use courses shorter than 13 holes to compute round ratings. So there's definitely going to be some amount of estimation/extrapolation involved in the DGCR system when it comes to things like 9-hole courses.

Yes, the current formulas are a bit glitchy, and are over-penalizing (based on their original intent) very short (especially 9-hole) courses in terms of their SSE, pushing them toward all birdies (or even an occasional ace). The revised formulas that I sent to timg (earlier in this thread) would have fixed that particular problem, but they presented some other potential accuracy problems with longer 9-hole courses. Realistically, in order to do a better job, the system needs to be redesigned a bit, but more importantly it needs a larger sample of 'real' PDGA SSA data. Collecting this is very difficult, unfortunately, because in addition to an SSA (which is pretty trivial to determine from looking at event results) we need to know the exact length of the event layout (per round, if it changes), and whether the course is 'lightly wooded', 'moderately wooded', or 'heavily wooded' (or more accurately how technical the course is, as sometimes those descriptors don't do justice to the actual layout technicality).

I'd love to do more work on the SSE formula system, but I'd need some more data contributions (of the type mentioned above) to really do much more than we already have. :p
 
Thanks! Interesting stuff.

I suppose someone's already proposed putting a "PDGA rating" entry on scorecard, so that you could calculate something more like an SSA from DGCR data? Along with a button something like "I checked the hole lengths carefully when I recorded my round." to help separate "high quality" data from possibly more dubious stuff? Was it simply dismissed as too complicated?
 
Last edited:
Thanks. Interesting stuff!

Since you specifically are looking for more SSA data, and more of the inputs sent to the PDGA, is your goal simply to reverse engineer the SSA? Is the formula not public?

From all the DGCR data I'd guess you'll soon, or already, have a wealth of raw data... Maybe of lower average quality than the PDGA stuff. Maybe we need a "I checked the hole lengths carefully" button on scorecard? As some kind of quick filter for "high quality" vs "dubious quality" data?

The actual SSA formula is not public, and depends solely on recorded rounds not on any course information. The starting point for the SSE formulas was Chuck's SSA estimation formula that is public and depends on length of the course. The SSE formula adjusted that for courses with different numbers of holes and added a variable for how wooded the course is.
 
The actual SSA formula is not public, and depends solely on recorded rounds not on any course information. The starting point for the SSE formulas was Chuck's SSA estimation formula that is public and depends on length of the course. The SSE formula adjusted that for courses with different numbers of holes and added a variable for how wooded the course is.

You manged to catch me in the middle of a series of edits. So, apologies to those who can no longer see the post mashnut is quoting ;)

But, anyway, you managed to latch onto a point that I thought I understood (mid-edit) - but maybe didn't.

Is the SSA process not public? I thought it was a relatively straightforward averaging of player's existing rankings, etc?
 
The basic process is public, but the exact formulas are proprietary. You can get very close estimations, look at some of jeverett's posts in other threads to find some that basically are identical, but those are reverse engineered by looking at data. It is reasonably straightforward, but a lot of other random stuff goes into it like figuring out propagators, dropping outlier rounds, determining the SSA, using that to determine the points per stroke, and using that to determine round ratings.
 
The basic process is public, but the exact formulas are proprietary. You can get very close estimations, look at some of jeverett's posts in other threads to find some that basically are identical, but those are reverse engineered by looking at data. It is reasonably straightforward, but a lot of other random stuff goes into it like figuring out propagators, dropping outlier rounds, determining the SSA, using that to determine the points per stroke, and using that to determine round ratings.

I have threads floating around with the (known) pieces of the PDGA ratings system in them, yeah. The full process has quite a few steps to it, but here they are in brief:

1). Determine who is a propagator, and the 'true' ratings of each propagator This is actually tricky to do externally. Propagators are players who have *at least* 8 prior rated rounds. These now nicely show up in bold print on event reports. However players without current PDGA memberships may still be propagators, a determination that cannot be done externally. Also, I believe that any player who is subject to the "888" ratings manipulation penalty actually is treated as having their 'full' rating for purposes of these calculations, another determination that cannot really be effectively done externally.

2). Compute the SSA, using linear regression. By comparing the (initial) player ratings of all with how they scored for the round (player rating on the x axis, round score on the y), compute the best-fit line. The point where this line hits 1000 rating points is the 'scratch score average' (SSA). Note: the assumption that the relationship between player rating and round score is linear is sometimes questionable, however this is confirmed as the method the PDGA uses.

3). Based on the determined SSA, calculate the rating-interval-per-throw, using the PDGA 'compression' formulas. I previously reverse-engineered these compression formulas using linear regression. These formulas are accurate to within 0.1% of the 'true' PDGA formulas:

For SSA's above 50.3289725:
Rating Increment = -0.225067 * SSA + 21.3858

For SSA's below 50.3289725:
Rating Increment = -0.487095 * SSA + 34.5734

Note: the assumption that the PDGA rating increment should be dependent exclusively on the SSA for the round is questionable. I've written a post about this topic elsewhere.

4). Compute round ratings. Here is the formula to do that, using the rating increment from step 3:

Round rating = (SSA - round_score) * rating_increment + 1000

5). Drop outliers. The PDGA method is a two-pass method, and excludes any propagator who's round initially rates in >60 points below their rating. So, if a 1000-rated player throws a round that rates in at a 930, that round gets dropped from step 2 above, and the above steps are calculated all over again (once all outliers have been removed). Note: the assumption that, once outliers have been removed, that all propagators' rounds are equally-meaningful is questionable, however this is the method the PDGA uses.

6). Using round ratings, periodically update player ratings. In the PDGA method, all rounds within one calendar year of the most recent round are included (initially) in a players' rating. If this is fewer than 8 total rounds, older rounds are included until at least 8 rounds are found. Of these rounds, those outside of (I believe it's just one) a standard deviation are not included in a players' rating. Of included rounds, the most-recent 25% are double-weighted.

*whew* Ok, that briefly covers every step. Make sense?
 
Last edited:
I'm not sure if this has been addressed already, but I don't really want to slog through all the previous posts :doh:. So sorry if this is redundant.

But I'm wondering about the value of including all of a players' rounds, even rounds that are by no means recent. I feel like the ratings for individual rounds are quite accurate, however, a player's composite rating has a tendency to be far from his/her true current rating if he/she has many rounds that are below their current standard, even if those rounds are well in the past.

For example, I have been playing this wonderful sport for ~3 years now. I've recorded nearly all my rounds since then, and have seen my individual round ratings go up significantly. When I started, I was shooting about 700, but have been shooting consistently over 900 :thmbup: for the past months. But my composite rating is still around 840 :(.

I realize that the most recent 25% (or similar) of one's rounds are weighted heavier, but that still gives old rounds a big part of the calculation. So I guess my question is: Would there be value/ Would it be possible to only use rounds within a certain time frame in overall ratings calculations?

Thanks!
 
Top