Rating Courses

[Larry_Warrilow]

a course rating system as a major factor in rankings has always been high on the wish list for we stat hounds. i agree with ernie that course ratings should evolve out of actual tour players statistics. a year and a half ago i worked up a limited model of a rating system based on the very best players results: the best winning stud score, all four rounds from the back tees, and one windy round, based on stats over three years. as a pilot project, the results for the six courses i used as a demo were pretty convincing, and i published the first half of the project on the forum on 5 april 2006.

shortly afterward indiebuilt bailed out, so publishing the second half seemed moot even though it had all the relevant math, and the method for arriving at a universal rating conversion factor. on the other hand, while basing difficulty ratings on the best players results is a valid method, the best players haven't in large part played the vast majority of apcds in competition, leaving many courses unrated, especially in the near future.

steve pitts, working on much the same problem, had developed an algorithm that could digest an entire difficulty level's stats not only in one event, but over a whole season on any given course, and i believe that that would also give a solid comparative course difficulty rating. even one weeks stats, given a large enough field, would give a good temporary number, as long as the conditions were not overly extreme. in fact, the larger the stat sample, the more any particular combination of conditions will cancel out.

having looked carefully at these stats in the past, i also believe that the relative difficulty rating of a course is a constant for all the links difficulty levels. the LC AI numbers, while consistant within themselves, still do not represent actual tour players experience on a given course, but would be an arbitrary place to start.

if mark still has records of tour play during previous indiebuilt or microsoft seasons, a ratings database for all LS and some apcd courses already exists.

in my rating scheme a tough course is arbitrarily picked as the baseline rating course and is assigned a rating of 1.00 (firestone fit this description in my example)[if another course is rated tougher later it would get a lower number: eg 0.98]. every other course gets a number in relation to this baseline course based on player stats. the higher the number, the easier the course: eg, firestone was 1.00, and innisbrook rated 1.008. thus, if a player shot a 70 at innisbrook he would multiply 70 x 1.008 for a 70.56 which would be the equivalent score at firestone. banf was rated at 1.1513, so a 70 shot at banf [70 x 1.1513=80.5] would be equivalent to an 80.5 at firestone. thus each 18 hole score can be compared in rating difficulty to any other by a constant multiplier (a relative difficulty conversion factor) that spans all levels. as a short example here are the six courses i chose for my initial exposition:

course/difficulty-rating/(70)score equivalent at firestone

firestone/1.00/70
innisbrook/1.008/70.56
castle pines/1.024/71.68
pelican hill/1.045/73.15
bountiful/1.086/76.02
banf/1.1513/80.5

these numbers were derived from actual winning scores shot by the best tour players over three years at these particular courses at champ. an analysis of just one large full field event at pro by the whole field might well yield very similar relative difficulty numbers. the point is that the ratings are based on actual links player experience. lw

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[Cheezer]

I like what Mark has come up with but I might add one thought. A course with undulating green conditons would be a really tough course using difficult pins and firm-fast would be a real brute but not nearly as hard if you used moderate-medium conditons.

Using Harbour Town the difference between difficult pins the difference between firm-fast and moderate-medium is almost negligable. But using a course like Cambridge Ridge the difference would be like night and day.

Taking in all the other factors that have been discussed how would could you adjust ratings for courses with the above scenerioes ? In other words if you used moderate-medium and moderate pin conditions to rate all courses but if the conditons for are set in a tourney for really tough conditons and pin placements it could throw off the ratings of some courses but not affect the ratings of the easier courses. COMMENTS ?

[Larry_Warrilow]

while cambrian ridge would have a very high difficulty rating whatever the conditions, one way of bringing into play numbers resulting from rare extreme conditions, would be to use all player scoring stats on a continuing basis for each course to update the course difficulty rating just as the player rankings are continually updated.

it's not likely that a rational course difficulty conversion factor will ever be able to even out the day to day differences in difficulty under extreme conditions for all courses for every round, but as the stats pile up over time, the exact conditions tend to cancel out in the final number, and that's about the best we are reasonably going to get. lw

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[Larry_Warrilow]

in reply to mark's original question, players voting on course difficulty is about the worst possible criterion. stats don't lie whatever the level or conditions. player rankings have been based on a weekly computer grinding of player stats, so why not overall course difficulty rankings. lw

[IBHackin]

One thing I might add is to contact Mike Schuetz. His old rankings system for Champ players in the past did keep stats on all courses and conditions. His ranking system was as good as I've ever seen. Might be worth looking into.

Steve

PM Mark if you want some contact information on him.

[Dr_Dave]

Hefty penalities...now I like that!! Lets see now, how about a good old fashion over the knee spanking for Phil Mickelson and Michelle Wie. I'll take care of Michelle, now we need a volunteer for Phil.

[RoyHiggi]

I have been reading this with interest and wonder if/how I could add something of value and I am not sure I can It sounds like picking up from whatever Mike Shuetz had done would be sensible but that presumably wouldnt cover many many of the courses out there now.

I wonder if ratings would be the same for amateur and elite. They don't come much easier than Harbour Town in amateur I wouldn't think but in elite its quite hard with all those trees actually coming into play.

No doubt there would be plenty of disagreement when ratings get announced but I am sure whatever was decided would be better than no ratings at all. The list of 6 LW included was interesting if I understood it properly. Firestone the hardest and Banff the easiest of the 6! Is that right? I think I would be OK with the order of those 6 except maybe with a switch of C Pines for Innisbrook at 2 and 3.Once you start putting 100 or more courses in a list I am sure it will be fine and the rating difference between courses will be fairly minimal anyway ( unless its the hardest v the easiest)

To save some work wouldn't it be sensible to just rate a course and forget trying to adjust ratings for all the different conditions you could encounter ( and only do it from back tees as well)

[lstouradmin]

Absolutely, Roy, I never intended to adjust the course rating based on conditions. I only meant that I would also adjust a person's ranking based on conditions played.

I love Larry's post. I need to think on it a little to see how I could implement something like that.

Mark

[canuck]

i would say take 40 or 50 set courses (perhaps the original ones from the old linkstour) then
let somebody here put some numbers/rating on those 50 courses.
something that mark can use possibly. larry warrilow

use this for awhile before adding extra courses to this list.

chris

[lstouradmin]

i would say take 40 or 50 set courses (perhaps the original ones from the old linkstour) then
let somebody here put some numbers/rating on those 50 courses.
something that mark can use possibly. larry warrilow

use this for awhile before adding extra courses to this list.

chris

Well, I was hoping we could find a way to make it pretty much automatic by using the rounds stored in the database. Of course that would also mean that course ratings might fluctuate slightly until we get a ton rounds played. We currently have 55,664 rounds out of 1,403 events stored since the last reset. Of those events, 532 were played using all 18 holes and the back tees.

Mark

[HeavySwinger]

My suggestion is this:

1. for APCDs which have AI player based ratings from Links Corner use that for first season. For stock courses which don't have AI ratings, use data from Larry_Warrilow analysis.

2. At end of season, do a LW type analysis and update the ratings.

I believe this effort will not only result in valid player rankings, but will form the basis of better handicap calculations.

[gibby]

Use your best judgement, If we are having 3,6,8 month seasons we can always tweak the numbers as we go along. Could take a year to get everything adjusted based on all the courses and players numbers.
We've all waited this long, so I think we could all wait a little longer to have a fair system put in place.

[Larry_Warrilow]

those limited rankings were based on the best winning scores of mostly three players at champ over three seasons: RoyHiggi, steve gomes, and giller. i had a number of events at each course from which to choose and all were from the back tees, included a windy round, and none of the players had any penalty strokes. roy may be right about innisbrook and castle pines, but his own scores were among those that established the relative difficulty ranking and those were pretty hard numbers. lw

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[ErnieB]

This is probably going to reopen some old wounds, but all those stats (LW's) were based on classic swing and as been pointed out by many in the past, Champ/Elite RTS is inherently easier than Champ/Elite Classic Swing - the main reason (IMO) is due to the fairway bunker bug in the game - while Pro RTS is inherently more difficult than Pro Classic Swing. Any ranking system would then need to be run separately for the three swing methods or, somehow, come up with a numerical multiplier to compensate for the ease or difficulty of the swing method/difficulty level being played if any stats for rankings are to come from events which allowed all swing methods to compete together.

(I'm not even going to start on the one tour for rankings rant )

[Bluenoser]

Good point Ernie.

I was hoping that there would be seperate rankings for each swing type along with an overall (all swing types combined) ranking.