Ron Klinger: The New WBF IMPs-to-VPs Scale

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ibpaAs known, the WBF decided to revise the scoring system and published a new VP scale, which will become the standard starting from Bali’s World Championships 2013. On May’s edition of IPBA bulletin, Ron Klinger published an interesting article, followed by the director’s comment, John Carruthers.  We publish here both contributes.

Ron Klinger. Under the new Victory Point scale adopted by the World Bridge Federation, every IMP counts (very good), but the IMPs vary in ever-decreasing fractions the more one scores. For the Ron Klinger (by E. van Ettinger)14-board scale used in the NEC Cup, IMPs 1 and 2 were worth 0.33 VPs each, IMPs 3 and 4 were worth 0.31 VPs each, IMP 5 = 0.30 VPs, IMPs 6 and 7 = 0.29 VPs and so on. Unless you memorize the scale, you have no way of checking your Victory Point score without consulting the relevant scale.

Another feature of the new scale is that it tilts the scores heavily in favour of small wins (making overtricks significantly more valuable). Under the former WBF scale, 0-2 IMPs was a draw for 14-board or 16-board matches. On the new scale 2 IMPs = 10.66–9.34 or a difference of 1.32 VPs compared to the draw previously. For 16-board matches, 3-7 IMPs used to be 16-14 in VPs, a difference of 2 VPs. On the new scale 7 IMPs = 12.16–7.84 VPs, a difference of 4.32 VPs, more than double the previous 2-VP difference.

It is very attractive to have every IMP count, but the scale could be greatly simplified and achieve virtually the same result with slightly less emphasis on small wins.

Suppose you want to cut the scale out at a maximum win of, say, 60 IMPs (16-board to 20-board matches). The first 20 IMPs could be scored at 0.25 VP each. Thus a 10-IMP win would be 12.5–7.5 (12.97–7.03 on the current scale) and a 20-IMP win would be 15.0–5.0 (15.26–4.74 on the current scale). It would also lessen the impact slightly for small wins: 2 IMPs = 10.5–9.5 (vs 10.66–9.34), 7 IMPs = 11.75–8.25 (vs 12.16–7.84).

IMPs 2-40 could be at 0.20 VPs each. Thus a 30-IMP win would be 17.0–3.0 (17.04–2.96) and a 40-IMP win = 19.0–1.0 (18.41 –1.59) IMPs 41-60 could be at 0.05 each.

 

Or, a slightly more even gradation could be:

IMPs 1-20 at 0.25 VPs each. 10-IMP win = 12.5 – 7.5; 20-IMP win = 15-5

IMPs 21-40 at 0.15 VPs each. 30-IMP win = 16.5 – 3.5; 40-IMP win = 18-2

IMPs 41-60 at 0.10 VPs each. 50-IMP win = 19.1; 60-IMP win = 20-0

 

If you wanted to cut out at 50 IMPs for a maximum win (12-15 board matches):

IMPs 1-20 at 0.25 VPs each. 20-IMP win = 15-5

IMPs 21-40 at 0.20 VPs each. 40-IMP win = 19-1

IMPs 41-50 at 0.10 VPs each. 50-IMP win = 20-0

 

If you want to make 40 IMPs a maximum win (8-11 board matches):

IMPs 1-20 at 0.30 VPs each. 20-IMP win = 16-4

IMPs 21-40 at 0.20 VPs each. 30-IMP win = 18-2, 40 IMPs win 20-0.

 

For 30 IMPs as a maximum win: 3-7 board matches:

IMPs 1-20 at 0.40 VPs each. 20-IMP win = 18-2

IMPs 21-30 at 0.20 VPs each. 30-IMP win = 20-0

 

For 1 or 2 board matches: 1 IMP = 1 VP up to a maximum of 20 VPs.

 

I am no mathematician, and those who produced the new WBF scales are, but it does seem attractive to make the WBF scales sIMPle and comprehensible to the average player. The preceding suggestions achieve the aim of having every IMP count and skew the scale less heavily in favour of the small wins. It also makes the scales easier to follow and allows anyone to work out the VPs using sIMPle arithmetic.

 

John CarruthersJohn Carruthers (IBPA Bulletin’s Editor). Agreed, simpler is better. However, do we need to accept the premise that “Every IMP counts”? I see no intrinsic merit in it. To illustrate why, consider the scoring at bridge from total points to IMPs. There are no decimal IMPs – every IMP has a range of points. A differential in team scores of 10 points even counts as 0 IMPs. So why is it necessary to make every IMP count? To my mind, having whole Victory Points is a more more laudable goal than making every IMP count.

 In an era when most jurisdictions are having difficulty attracting new players (especially young ones) to the game, we should be doing all we can to simplify scoring, not complicate it. Moves such as this to decimal scoring reduce the accessibility of the game to the uninitiated. A better move would have been to make every IMP worth one Victory Point or to make every board a point. Decimal Victory Points are an abomination! What is next on this continuum – making every point count for decimal IMPs? 

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 Read the previous discussion: Carruthers Klinger and Bramley about new Victory Points Scales

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IBPA Bulletin No 580 – May 10, 2013

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