FIXED TOTAL VALIDITY SCORING

by D Tim Cummings - 26th March 2001

How to fairly compare only the best flights of different pilots in a competition with different validities on different days.

THE PROBLEM

The GAP scoring system was designed assuming that the results of ALL flights would be totalled to give an overall competition result. Because of this, GAP is able to give different days, different validities to take into account the effects of luck on dodgy days. Each pilot's total is a fair comparison because each pilot had the same opportunity to score the same maximum score.

Sometimes we can't or don't want to include all days to give a total score. Examples are:

  • A weekend competition series where pilots can't turn up every weekend.
  • The paragliding round by round ladder calculations.
  • We want to encourage racing by allowing pilots to drop their worst flight(s) in a comp.

    • BAD SOLUTION ONE - Take scores from a fixed number of rounds

    This solution is the easiest solution to implement, and so is very tempting to comp organisers. It is the current method used in the PG national ladder. Unfortunately, what happens in practice is that a pilot's "best" days become the high validity days that the pilot flew, instead of the days the pilot flew best. I have seen the ridiculous situation where a pilot keeps the high validity day where he bombed out and throws away the low validity day that he won.

    BAD SOLUTION TWO - Remove day validity concept

    This makes it possible to score 1000 points on any day. Our experience shows that the validity concept is a useful one in rewarding pilot skill more than pilot luck. This solution is fair in that every pilot gets a total score from flights with the same maximum possible score. It is not fair in that it can reward a pilot with 1000 points who by luck flew into the only thermal out of launch.

    THE GOOD SOLUTION - Fixed Total Validity Scoring

    Fixed Total Validity Scoring solves these problems by preserving the validity concept to identify the luck factor, but keeping the maximum possible score for all pilots the same. That way the total is a fair comparison of how well the pilot flew.

    How it works

    For all the flights of a pilot:

  • Calculate a performance percentage for each day by dividing the pilot's day score by the day validity (day quality factor).
  • Arrange all flights in descending order of performance percentage.
  • Total up the flights' raw day scores (not performance percentages) in order of performance percentage until the sum of validities for those scores reaches the predecided FIXED TOTAL VALIDITY value.
  • If the last score added takes that pilot's total validity above the FIXED TOTAL VALIDITY then only a fration of that score is used so that the pilot's total validity is equal to the FIXED TOTAL VALIDITY.

    • Winners Scores or Day Validities

    Why not calculate a performance percentage by dividing the pilot's day score by the winner's day score? There are two reasons for this. Firstly GAP wants to reward a pilot for leading out and flying fast. On any day there are three winners, first to leave to make goal, first to arrive in goal and fastest to goal.

    By using day validities instead of winners score we are preserving the GAP concept of only giving the maximum possible points to the pilot who wins all three "events".

    The second advantage is probably more likely to be seen in a ladder calculation which only needs half of the overall flights. It would be possible for two pilots to each win half of the days and they would end with the same scores on the ladder.