http://www.fai.org/hang_gliding/meetings/plenary/2007


D Tim Cummings, HGFA CIVL Delegate from Australia, writes:

Australia proposes that Fixed Total Validity (FTV) be adopted and
used with the Race scoring system


Fixed Total Validity (FTV) is a procedure for fairly scoring competitor's on
only their best rounds rather than all their rounds.  Fixed Total Validity means
the sum (total) of available points (validity) is set (fixed) to the same value
for each competitor.


If all rounds are included in a total score, then the total validity is
automatically the same for everyone.  However, sometimes we can't or don't want
to include the results of all competition days to give a competitor's total
score. Examples are:


- A weekend competition series where pilots can't turn up every weekend.


- The paragliding round by round ladder calculations.


- Encouraging racing by only scoring a pilot's best flights in a competition


This is achieved with Fixed Total Validity (FTV).  Fixed total validity is an
adjustment that can be applied to results from any scoring system which has
different validities, or a different number of available points, in each round.
Fixed total validity requires a single parameter, FTV Reject Rate. 


For a competition over consecutive days, where the motivation is to encourage
racing, we recommend an FTV Reject Rate of 20%.  If all days were equally valid,
this is equivalent to dropping one round in five.  For a weekend competition,
where many competitors simply cannot turn up every weekend, we recommend an FTV
Reject Rate of 30%.  This is equivalent to dropping three days in ten, if all
days were equally valid.  For a round by round ladder we recommend an FTV Reject
rate of 30%.


The FTV procedure is simple in concept, but can get confusing when implementing
the calculations.  Remember to distinguish between score = the number of points
earned by the competitor available points = the round validity or maximum
possible score, not necessarily the winner's score.


Winners Scores or Day Validities


It is important to use validities rather than winner's score when calculating
available points.  GAP and OzGap have reasons for not awarding the winner with
the full number of available points and we need to preserve this.  Reasons
include, not making goal, not being fastest on day, not being first to goal.


FTV Software


Software is available from the HGFA website that can automatically modify a RACE
data file to adjust for FTV.  It can run on any computer that runs RACE.  It
requires MS Access 2000 or MS Access 2000 runtime (separate download).

Here is the simple version. After five task days you (and everyone
else) get to drop your worst day, with the worst day being being defined as the
day you do your worst compared to the competition.