[blml] Thai braking [SEC=UNOFFICIAL]

[Nigel]

[Richard Hills]

An problem with the standard WBF Victory Point
scale is the issue of "breakage".  That is, the
majority of imps scored are worth nothing, but
a minority of particular imps are worth a full
victory point.

For example, if to gain 17-13 VP win you need
6-8 imps, your sixth imp is worth a victory
point, but your seventh imp or eighth imp are
arbitrarily deemed to be irrelevant.

Another problem with the standard WBF Victory
Point is that the scale is too compressed.

With only 26 possible VP scores for a team (and
the majority of VP results in teams matches
resulting in more bunched possibilities), it is
quite likely for two or more teams to have an
exact tie for a critical place.

One solution is to convert imps to VPs on the
basis of 1 imp = 1 VP.  This is also less than
satisfactory, since it excessively rewards
those expert teams who regularly narrowly lose
to other expert teams, but also regularly bunny
bash weaker teams by huge margins.

My local Bridge Federation of the ACT is
experimenting with fractional VPs, retaining the
logarithmic nature of the WBF Victory Point
scale, but ensuring that each individual imp is
worth something.  Here is the BFACT modification
of the WBF Victory Point scale for 9-board
matches:

Imp difference    Winning VPs       Losing VPs
0                 15.00             15.00
1                 15.30             14.70
2                 15.65             14.35
3                 15.95             14.05
4                 16.15             13.85
5                 16.40             13.60
6                 16.65             13.35
7                 16.90             13.10
8                 17.20             12.80
9                 17.55             12.45
10                17.90             12.10
11                18.25             11.75
12                18.60             11.40
13                18.95             11.05
14                19.30             10.70
15                19.65             10.35
16                20.00             10.00
17                20.35             09.65
18                20.70             09.30
19                21.05             08.95
20                21.40             08.60
21                21.75             08.25
22                22.10             07.90
23                22.45             07.55
24                22.80             07.20
25                23.15             06.85
26                23.50             06.50
27                23.80             06.20
28                24.10             05.90
29                24.40             05.60
30                24.70             05.30
31                25.00             05.00
32                25.00             04.75
33                25.00             04.50
34                25.00             04.25
35                25.00             04.00
36                25.00             03.75
37                25.00             03.50
38                25.00             03.25
39                25.00             03.00
40                25.00             02.75
41                25.00             02.50
42                25.00             02.25
43                25.00             02.00
44                25.00             01.80
45                25.00             01.60
46                25.00             01.40
47                25.00             01.20
48                25.00             01.00
49                25.00             00.80
50                25.00             00.60
51                25.00             00.40
52                25.00             00.20
53                25.00             00.00


[nige1]
Brilliant Richard! Now that most competitions are scored on computer, fractional scales seem to be an improvement. Also, like BFACT, all VP scales should specify an earlier cut-off for winning than losing.