Combined ratings on 2 day events.

[Cgkdisc]

At the beginning of doing ratings, we didn't know what the statistical parameters were for various elements in the system. So we collected data and kept the round values separate. As we gradually learned the parameters, we were able to not only make it better statistically but in human terms.

There are choices made for member satisfaction reasons. Combining/not combining is a statistical choice we made toward combining when statistically appropriate because members are happier when they get the same rating for the same score on the same layout under what they perceive were similar weather conditions.

 

[BogeyNoMore]

Here's an exaggerated example to keep the math simple. Let's say one round produces a 50 SSA and another round produces 51 on the same layout. Let's say the first round had no wind and there was a light breeze in the 51 round. Let's say there's a 95% chance that the SSA produced under no wind ranges from 48-52 for this smaller pool of propagators and it's 49-53 for the round in the breeze.

If all the ratings team knows is the 50 & 51 on the same layout and nothing about the wind, statistically we know these two rounds could have been thrown in similar conditions so we combine them. Even if the TD says the second round was windy, the numbers are not far enough apart for us to be sure there's a reason to rate them separately.

In fact, the numbers and probable variance ranges overlap enough that it's possible the 51 SSA was produced during no wind and the 50 was produced with the wind. If we kept these rounds rated separately, players would wonder what's going on when they knew the windier conditions were "tougher". That's what happens on a regular basis when you see unofficial ratings where a windier round gets lower ratings for the same score. It's just the normal variance in the precision of the ratings process, especially with a low number of propagators. Once the two rounds are combined, players end up with official ratings with the same score getting the same rating.

So it's better to rely on an objective statistics process to determine whether to combine or separate rather than specifically rely on whether the TD posts the weather report. It's more consistent for everyone.

At the risk of sounding ignorant (I'm not really sure how SSA's are calculated): I wouldn't think a difference of 1 in the SSA (as in the example abouve) would indicate a substantial difference in conditions... wouldn't expect these rounds not to be combined... there's doesn't seem to be any statistical data to support doing so.

However, isn't it possible for R1 to have an SSA of 50, and the same players play R2 (same layout) the next day with rain and 25-30 mph winds, resulting in an SSA of 54 or 55? If, as a group, the same players get about 4-5 extra strokes on the same layout, doesn't that speak to the fact the conditions likely were substantially different? Perhaps the TD's comments simply confirm it?

I can't help but think I've missed a key point somewhere... :\

 

[JC17393]

At the risk of sounding ignorant (I'm not really sure how SSA's are calculated): I wouldn't think a difference of 1 in the SSA (as in the example abouve) would indicate a substantial difference in conditions... wouldn't expect these rounds not to be combined... there's doesn't seem to be any statistical data to support doing so.

However, isn't it possible for R1 to have an SSA of 50, and the same players play R2 (same layout) the next day with rain and 25-30 mph winds, resulting in an SSA of 54 or 55? If, as a group, the same players get about 4-5 extra strokes on the same layout, doesn't that speak to the fact the conditions likely were substantially different? Perhaps the TD's comments simply confirm it?

If the SSAs come out that far apart, they're very likely not going to combine those rounds based solely on that fact. Confirmation of conditions from the TD would be nice, but it would still be unnecessary as far as the decision making process goes.

 

[mashnut]

At the risk of sounding ignorant (I'm not really sure how SSA's are calculated): I wouldn't think a difference of 1 in the SSA (as in the example abouve) would indicate a substantial difference in conditions... wouldn't expect these rounds not to be combined... there's doesn't seem to be any statistical data to support doing so.

However, isn't it possible for R1 to have an SSA of 50, and the same players play R2 (same layout) the next day with rain and 25-30 mph winds, resulting in an SSA of 54 or 55? If, as a group, the same players get about 4-5 extra strokes on the same layout, doesn't that speak to the fact the conditions likely were substantially different? Perhaps the TD's comments simply confirm it?

I can't help but think I've missed a key point somewhere... :\

What you're missing is that if the two rounds have 50 and 54 SSAs they won't be combined. You're right that 50 and 51 is not a very significant difference but 50 and 54 is. That's true regardless of what the TD does or doesn't write on the TD report about weather conditions.

 

[DavidSauls]

The O.P. cited a 25-point difference in unofficial round ratings, later combined. I'd guess that was 2.5 difference in SSA. So, somewhere in between

 

[JC17393]

The O.P. cited a 25-point difference in unofficial round ratings, later combined. I'd guess that was 2.5 difference in SSA. So, somewhere in between

The unofficial calculation isn't the same process as the official one though. So what was 25 points difference in the unofficial might have only turned out to be 15 or maybe less in the official calculation.

 

[Cgkdisc]

Here are some of our combine/not combine breaks for official ratings:
Less than 12 propagators - combine if SSA difference less than 4.0
Over 60 propagators - combine if SSA difference is less than 2.0

The decision process gets more complicated if there are more than two rounds on the same layout over more than two days.

 

[BogeyNoMore]

If the SSAs come out that far apart, they're very likely not going to combine those rounds based solely on that fact. Confirmation of conditions from the TD would be nice, but it would still be unnecessary as far as the decision making process goes.

What you're missing is that if the two rounds have 50 and 54 SSAs they won't be combined. You're right that 50 and 51 is not a very significant difference but 50 and 54 is. That's true regardless of what the TD does or doesn't write on the TD report about weather conditions.

Got it - makes perfect sense: if the scores don't indicate things were statistically different, then there's no reason to treat rounds differently.

If the data indicates "all things are not equal," then they're rated separately.

The possibility for "error" exists for pretty unlikely extremes:
a) Conditions truly suck in one round, but on the whole, players shoot so well they overcome them such that the SSA is similar.
b) Conditions are great, but players shoot so poorly in the nice weather round is indistinguishable from the crappy weather round.

Pretty improbable, and in either case, impossible to tell which round is the aberration since statistically, there's no appreciable difference

 

[bombmk]

There are choices made for member satisfaction reasons. Combining/not combining is a statistical choice we made toward combining when statistically appropriate because members are happier when they get the same rating for the same score on the same layout under what they perceive were similar weather conditions.

Which brings us back to the anecdotal. And my experience differs. People do not want to get the same rating for the same score, when they can see that score being better in one round than the other. We are told we are playing the field. Again; You might have access to a larger sample size of complaints, so it might just be my experience.

But fudging the numbers to make people happy is just.. yeah, I don't get it.

 

[krupicka]

I've heard plenty of complaints when one round is rated differently than the other. Players see the unofficial ratings and wonder why Saturday's round was rated differently than Sunday's round. I have to assure them that when the official ratings some out they will most likely have the same rating.

It is not fudging the numbers. It is a decision as to whether or not rounds on the same layout at two separate times are one data set or two. Comparing them statistically is really the best way to determine that.

 

[jjpitt29]

How about rounds in different years? If you have the same layout in relatively similar conditions from one year to the next shouldn't the ratings be pretty close to the same?

 

[Cgkdisc]

They should be within the same standard deviation range.

 

[bombmk]

It is not fudging the numbers. It is a decision as to whether or not rounds on the same layout at two separate times are one data set or two. Comparing them statistically is really the best way to determine that.

If you are bent on combining rounds, yes, it is the best way to do it.

But what is done is "These rounds could have been played in the same conditions - so they must have been". That catches some who were actually not.

Why not let the rounds stand on their own and leave the averaging to the player rating calculations?

 

[JC17393]

If you are bent on combining rounds, yes, it is the best way to do it.

But what is done is "These rounds could have been played in the same conditions - so they must have been". That catches some who were actually not.

Why not let the rounds stand on their own and leave the averaging to the player rating calculations?

If there is no significant statistical difference between two rounds, why should it matter at all what the conditions were in either round? Clearly the conditions were not a factor in making the course easier or harder for either round, so why treat them separately based solely on that non-factor?

 

[DavidSauls]

If you are bent on combining rounds, yes, it is the best way to do it.

But what is done is "These rounds could have been played in the same conditions - so they must have been". That catches some who were actually not.

Why not let the rounds stand on their own and leave the averaging to the player rating calculations?

Elsewhere, there are people griping because the unofficial ratings of 2 rounds, played under near-identical conditions, don't match. Though it's mostly just the variability of a small sample, they see it as a flaw in the ratings system.

At least those people will be happy, or less grumpy, once the ratings for those rounds are matched.