also, personally, there is another avg stat I'd like to see in addition to that mentioned above, which is avg net over par. This would take the player's course handicap into consideration.
Our index excludes our worst 10 our of 20 last rounds. Basically the above would include those bad rounds, and we'd see essentially just how badly we tend to play when we aren't playing close to our index, while taking the rating/slope into consideration as well.
Then let's say my average net over par is +1.5, which says that including all my bad rounds and good rounds, factoring in course handicaps each time; over all, I end up net +1.5 over on average.
By knowing that, I can approach a course, and calculate my course handicap for it. let's say course handicap is 22 on a par 72 course with a rating of 72.2 I add 72.2+22+1.5 = 95.7, round up to 96 That becomes my status quo for how I've been playing past 20 games. If I play below 96 (on that course) I'm doing better than average and over 96 would be worse then average. An even 96 would be right on par for how I've been playing, on that particular course.
To me, this is the most interesting way to use our index to gauge how we're playing any particular round. It helps us to set expectations for ourselves that matches our current reality and the course we're playing on.
However, over time I don't expect this value to change much unless we become a more consistent player in general, in which case, the more consistent we are, the smaller it would become as an average. A large value would indicate big swings in our scoring and inconsistency, with bad games being REALLY bad.
The above statistic would basically provide a way to give a player a goal, the iphone app could provide a score goal, if our status quo for a given course based on our past 20 games, was say 96, as calculated above then it could display 95 as the goal. Any score of 95 or better would then be considered better than average for the given player on the given course, and reason to rejoice.
There might be a better way to do this by using differentials somehow, but include all past scores for a given period of time, either past 20 or this year or whatever, not just the best 10 past scores. Average differential.