[matmat]

brianshark, on Apr 23 2009, 07:46 AM, said:

Another reason: Perhaps having two teams set out to win, as opposed to two teams setting out to "not lose" (if a draw is available) makes for a more interesting spectacle for the viewing public.

especially at 3am in the 18th inning

[mycroft]

30-VP is de rigeur in Ontario and Quebec as well. It's just a matter of location and tradition.

ACBL 20VP is a decent, short-board scale. I think the WBF scale works much better as the board count expands. 30VP is "Win-loss, with tiebreaks for the directors." Note that in ACBL W/L, a win by 1 or 2 counts as .75 (and similarly a "losing tie" is .25) - win by 3 on the 30 scale is 20-10.

Not that "tiebreaks for the directors" is necessarily a bad thing, you know...

[Trinidad]

The correct VP scales depend on the number of boards played. The IMP difference that you need to win to achieve a certain VP score scales with the square root of the number of boards played. (Mathematicians will tell you why that is the case.)

As an example, to achieve a 25-0 score for a 32 board match, you will need to beat the opponents by more than 100 IMPs. In an 8 board match four times less boards are played compared to a 32 board match. Therefore, for an 8 board match you will need more than 100/sqrt(4)=50 IMPs difference to score 25-0.

The 'standard 30 VP scale' (if there is such a thing, since it isn't dictated by the Laws of bridge) is for 32 boards. All other 30 VP scales are derived from that by multiplying the IMP ranges by sqrt(N/32). See e.g. http://homepage.mac.com/bridgeguys/VGlossa...Conversion.html

Rik