This is the way Queenstown Bridge Club Members' Handicaps are calculated:
Handicaps are calculated by taking 50 - (the player's average score over the previous year) X 1.
E.g. Jo Bloggs has an average over the last year (excluding Championship Pairs and Robinson Graded Pairs) of 48%
So: 50 - 48 = +2
Handicaps are updated at the end of each series.