Ask Chuck Kennedy

[ck34]

I don't even know how it all works for the groupings. In the beginning of the year, players don't end up on their state lists until they have played. I think all pros of all ages are in their gender list but I'm not sure GMs and SGMs show up on the Master list (but should). It's a mess and I don't like having to apologize for the PDGA every time players want what would seem like easy sorts and selections to achieve. This has gone on for years now and it's finally getting higher on the budget priorities. Someone not only has to volunteer to do it but someone has to oversee it because the website is so convoluted, from what I understand, that it's easy to do something here and mess up something there.

[AviarX]

as i said before -- thanks Chuck. It looks like it will be really cool when all the updates get put in place. i do tend to associate PDGA stats with you and it didn't make sense that something you are associated with wasn't nearly perfect. thanks for reinforcing that impression by expressing your dismay with some of the loose ends

[AviarX]

from what I understand, that it's easy to do something here and mess up something there.

that seems true of course design and disc golf play too ...
hey, wait a minute ... -- isn't that just a cliche with universal applicability?

[dave_marchant]

Chuck - Here's a ratings question that I'm sure has been answered, but I missed it (and it is a hard one to seach for):

Why do historical events have current ratings listed along side the competitors?

It would be so much more valuable and make so much more sense to list their historical rating that matches the date of the event. The data is in the database so it seems like a minor coding change.

[ck34]

This hasn't risen high enough in the priorities for IT folks to change the code to pull each player's historical rating value rather than their current rating. It's not necessarily a trivial process since players don't have ratings populated into each update field in the database if they didn't have an update that period. So some calculation is required to find their most recent rating prior to that event date. I agree it would be better to retain the rating the person had leading into the event so you can maybe see how players have progressed over the years.

[dave_marchant]

Thanks for the explanation. You are right - it would take a little intelligence to be able grab the most recent rating before the event. But I can't imagine it would be too complicated in comparison to a lot of the searches/calculations that currently spit out data from the ratings database.

You can actually see players' progress really well in the "ratings history" part of each player's stats. That bar graph is cool. But when looking at events from years past, it is a pain to click on each player to get a real-time historical snapshot (and then have to remember it all).

As usual, thanks for all the work you and the team do to make this stuff so accessible!

[accidentalROLLER]

Chuck,
Setup to Question: The other day some of my buddies out at the course were doing a make-shift handicapping system using their player ratings. The way they did it was a stroke for every 10 points. I seem to remember you explaining exactly how much a stroke was worth in ratings points a long time ago. So I was wondering.....
Question: On a par 54 course with an SSA of 47.48, how many ratings points would a stroke be?
Sidenote: If this has a very complicated answer involving supercomputer calculations, just say too complicated.
Thanks.

[ck34]

Three options: The easy way is to look up some courses on this website to find those with SSA close to the one you're planning to play. Click on the event that produced the ratings for that course and see how much each throw was worth by looking at the round ratings for people one shot apart.
http://www.pdga.com/tournament/cours..._by_course.php

Another option is to subscribe to the Disc Golf United handicapping service ($19.95/yr or $2.95/mon) which does all of the math for you and tracks your personal numbers. http://www.discgolfunited.com

Another option is to download the Excel template for calculating ratings.
http://www.pdga.com/competition/rati...temp06plus.xls
Enter a fake player with 1000 rating and put the actual SSA in as their score. Make sure to enter 18 for the number of holes at the top. Then, enter a second player without a rating who has a score exactly one shot higher or lower than the SSA. awitch to the tab that has the ratings on it and look what the difference is between the ratings of those two players.

[accidentalROLLER]

Thanks Chuck. I think option 3 will work. So I guess once I put the numbers in it will answer the other question I had in mind of "is the ratings scale linear?".

[ck34]

For a given SSA, each shot is worth the same so that part is linear. But the number of rating points per throw does not change in a linear fashion with a one shot change in SSA.

[DSproAVIAR]

Chuck, I have a question. Will the second round for the Open div at this tournament be rated? Only the 4 Open players played the long tees second round.

[ck34]

It probably will get rated under our new approach. When there are fewer than 5 propagators on a course, if that same group (and others) play the same course in another round, we will combine the results for both rounds to do the ratings in one batch for both rounds.

[DSproAVIAR]

Oh man that sucks.

But thanks!

[ck34]

Well, the good news is that if only one of those rounds ends up getting double weighted for your April rating update, at least it will be the better one.

[DSproAVIAR]

I think they both will. I've only got 3 tourneys coming up before 4/10.
Is that always the case, for any tournament that only has 1 round double-weighted? That would be cool.

[ck34]

No. It depends on where the 25% line breaks for you at each update. If you have 20 rounds in the update, your most recent 5 will be double weighted. If your most recent events are each 2 rounds, then only one round in the event just before those two will be double weighted and we always use the best of the two.

[jmonny]

Chuck....I just recently had a sweeet round that was unofficially 71 points below my current rating. Is there a way I can calculate if that round will be excluded or not in the next update or will I have to wait?
Thanks...#21433

[ck34]

Calculate the standard deviation of the ratings for the rounds you think will be included in the next update making sure to drop out rounds more than 12 months older than the date of the most recent round you think will get reported before the next update. If your standard deviation is less than 28, it's likely your round will be excluded. Remember though, it's how many points below your new rating that counts, not your current rating when determining if any round gets dropped.

[magilla]

Calculate the standard deviation of the ratings for the rounds you think will be included in the next update making sure to drop out rounds more than 12 months older than the date of the most recent round you think will get reported before the next update. If your standard deviation is less than 28, it's likely your round will be excluded. Remember though, it's how many points below your new rating that counts, not your current rating when determining if any round gets dropped.

THATS why I got $#@!$%^ from that round at the Great Northwest Open....

[lonhart]

Hi Chuck,

You posted the following quote in another thread.

"It can happen online for unofficial ratings but not in reality. ALWAYS almost exactly the same number of players will end up with ratings higher than their rating and half lower on any layout. It's not possible for it to happen any other way for official ratings. When you see oddities like you're talking about, it just means the course layouts haven't been done properly yet. There's not even a boost factor anymore which did actually produce a few more higher ratings than lower ratings during 2005. But that's gone. "

Can you explain why half the players tend to be rated (and hence play) above their rating while the other half are rated below their current rating? You used "ALWAYS" as though there was a statistical reason, and if so, I'd like to read more.

Thanks!
Steve

[ck34]

The SSA course rating for each round is determined by the average rating of the propagator players and their average score for the round. The round ratings are then based on that SSA from the scores. The average rating of the propagators will always be the same as the average of the round ratings except when we had a boost factor in there that shifted the calculated SSA 0.1 to 0.5 higher during 2005 and part of 2006 when it was phased out. During that time, the average of the round ratings was 1 to 5 points higher than the average rating of the propagators. Now it should be close to the same. It's not always perfect due to rounding and a slight shift in the formula to account for a really shallow curve in the equations to adjust for lower rated propagator groups versus higher rated propagator groups.

[wolfpackgolfer]

Chuck,

I have 10 rounds of golf that will be going into the new ratings when they update. 4 at the buckhorn open, 4 at the coastal plains winter open, and 2 from the loriella challenge. I know that some rounds are doubled to emphasize how well you play the most recently. I was just curious how many rounds will be doubled and maybe just a reader's digest version of how ratings are determined. Thanks.

[ck34]

All rounds going back 12 months from the date of your most recent event will be included. The most recent 25% (1 out of 4) will be double weighted. If any rounds are more than 2.5 standard deviations below your average will be dropped which is about 1 in 50.

[wolfpackgolfer]

so when you say the most recent 25% are doubled, is that the most recent of all the rounds that are being used for the ratings, or 25% of the new rounds that are going into the ratings since the last ratings update?

[ck34]

25% of the total number of rounds going back 12 months that are included in your update, not just the new ones.

[wolfpackgolfer]

so basically it's an ave of all your rounds over the past year with just a couple dropped and the latest 25% doubled?

[ck34]

Yes. But everyone's 12 months is different. It's all rounds in the 12 months before the date of your most recent round in the update. If your most recent round is January 15th, then we go back to January 16th of 2006. If it's March 3rd then we go back to March 4th of 2006.

[wolfpackgolfer]

great thanks chuck

[deathbypar]

Chuck, what would my rating be if Am Worlds 06 were excluded? I had a cast over my elbow for that tournament.

[ck34]

I don't know. It will drop off in the late August update as long as you play an event after July 29th this year that gets reported for that August update.