JHern: yeah, there is definitely some variance. I was mandatory advanced for one rating update but didn't play a tournament. the next year there was a rule change.

A long time ago (the first 2 years of ratings) i remember wondering why certain areas seemed to be "heavy" with high rated players while other areas were "light." after a while, i realized the average course difficulty in said area can skew the ratings in one way or another.

Around 2004 I developed a calculation for how to predict the winning score for a course in the pro division (this requires at least one player rated ~1000 in attendance).

This year i've been working with an am2 player that plays LOTS of tournaments and I was able to predict the winning am2 score over 2 rounds within 1 stroke in 5 straight tournaments. I then developed a calculation that fairly accurately predicts that as well.

when you compare the average winning scores of MPO vs. AM2 it explains both what I wrote before about raising your rating if you are rated under 930 and why certain areas have more higher rated pros.

A few quick definitions:

MPO Birdie Opportunity* = a hole that can be birdied with a nearly perfect 450' drive and a 50' putt.

Trouble Hole = a hole that has leaves a strong chance for bogey if you throw an errant tee shot (thick schule, OB, etc.).

AM2 Birdie Opportunity** = a hole that can be birdied with a nearly perfect 380' drive and a 30' putt.

To predict the single round score average that will win MPO:

Winning MPO average round score = MPO Birdie Ops x 0.7 - Trouble Hole x 0.25

multiply this by the number of rounds to get the total score prediction.

Note: in nearly every tournament someone in MPO will shoot a single round score better than the predicted winning score, but the overall winning score will usually be within 0-3 strokes of the total score predicted by the formula.

For an example:

http://www.playdg.com/courses/?s=MN&c=kaposia(this is not the current kaposia layout, but will work for the calculation)

MPO birdie ops: 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 18 (10 and 17 play longer than measured) = 16 MPOBO

Trouble Holes: 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16 = 12 TH

Predicted average round score to win pro: -8.2 (-16.4 for 2 rounds, - 24.6 for 3 rounds, etc.)

For Am2, the calculation differs a bit.

Winning average score = AM2 birdie ops * 0.5 - Trouble holes * 0.5

AM2 Birdie ops: 1, 2, 3, 4, 5 (short only), 6 (short only), 7, 9, 11, 12, 14, 15, 16, 18 = 14 short, 12 long

Winning average score for AM2 = -1 in the shorts, E in the longs.

Average difference in score for winning pro vs. AM2 = 7.2 to 8.2 strokes. (14.4 to 16.4 strokes across 2 rounds).

the trouble hole % is really what kills lower rated players more on harder courses.

If you take a course of similar length to the sample but reduce it to 4 trouble holes instead of 12 and you get:

MPO predicted winning round score: -10.2

AM2 predicted winning round score: -5 in the shorts, -4 in the longs.

Average stroke difference between MPO and AM2: 5.2 to 6.2 strokes per round.

increasing course length and the number of trouble holes will really drag the AM2 scores down but the pro scores will only decrease by a little bit.

at the same time, this calculation breaks down if you played a course with all 18 holes under 400' and no trouble holes. This predicts that pros will need to average a -12.6 per round to win, which is very realistic. It predicts that Am2 will need to average a -9 to win... which is unrealistic. On a course like this there will probably be an Am2 that shoots a -9 in each round, but the winning score will probably be more like a -6 average per round since i don't think most Am2's are consistent enough to throw consecutive -9's, even on an easy course.

* for larger events, such as NT's and majors, increase the drive length to 480'. to retrofit pre-wraith tournaments use 450' for majors and 430' for standard tourneys.

** the 380' marker has been adjusted for technology. to retrofit these to pre-wraith tournaments use a 350' drive as the Am2 birdie op range.