Rob Boudrie - USPSA L1571

July 31, 2001, Revised August 9, 2001

Updated August 9, 2001

The HFx Scoring, proposed in the agenda of the 2001 General Assembly (available at www.uspsa.org/members), specifies that each stage score be multiplied by a "stage multiplier" which is the "average stage hit factor" divided by "average match hit factor". That proposal states that the possibility of flipping (one shooter's score affecting the relative finish of two other shooters) is not present with HFx scoring..

Contrary to this assertion (#1 in the GA Agenda HFx proposal), it is possible for the scores of two competitors to flip-flop based on the score of another competitor.

The first revision of this analysis used the stage points based on a 100% hit value for each stage, rather than calculating stage points based on "hit factor * minimum rounds required * stage multiplier". This version of the analysis has corrected that misunderstanding.

If anyone can sees a flaw in these calculations or conclusions, please bring it to the attention of Rob Boudrie. If my calculations or conclusions are found to be in error, I will publish an immediate correction.

This is best illustrated by example. Take the case of the following hypothetical two stage match with three competitors, a 12 round stage and a 24 round stage.

Example

First, consider a set of results where Moe beats Larry : (this spreadsheet is available in MS/Excell form at www.boudrie.com/hfx.xls.

 

Stage 1

Stage 2

H.F.

Rounds

Multiplier

Points

H.F.

Rounds

Multiplier

Points

Total

Moe

9.10

12

0.81

88.43

12.00

24

1.190

343

431.21

Larry

8.00

12

0.81

77.74

12.36

24

1.190

353

430.80

Curley

9.00

12

0.81

87.46

14.00

24

1.190

400

487.36

Stage Avg

8.70

12.79

Match Avg:

10.74

Observe the outcome if the hit factor for Curley is changed from 9.00 to 7.00. Larry now beats Moe as a result of a change in Curley's score:

 

Stage 1

Stage 2

H.F.

Rounds

Multiplier

Points

H.F.

Rounds

Multiplier

Points

Total

Moe

9.10

12

0.77

84.27

12.00

24

1.228

354

438.02

Larry

8.00

12

0.77

74.08

12.36

24

1.228

364

438.45

Curley

7.00

12

0.77

64.82

14.00

24

1.228

413

477.53

Stage Avg

8.03

12.79

Match Avg:

10.41

The use of average hit factors (for both stages and the entire match) bases each individual's scores on their own performance as related to other competitors. HFx does not deliver benefit #1 (no possibility of scores "flipping" mentioned in the 2001 General Assembly agenda. It appears that the reason HFx generates results so close to the current scoring method is because it also scores each competitor's performance relative to others.

The statement made under benefit #3 (Real-Time results) is inaccurate since all scores are required to calculate the average. Results, both relative and absolute, are available only after all scores have been entered into the computer.

Likewise, the assertion made in item #5 "an individual's scores are not affected by any other shooters [sic] performance" is inaccurate. As the above example shows, scores can flip.