[blml] Thai braking [SEC=UNOFFICIAL]

[richard.hills at immi.gov.au]

Robert Geller:

[snip]

>In the first place, Swiss events have a huge luck factor,
>due to the randomness of the matches (greatly variable
>strength of opponents).   Indeed, this is probably
>precisely why Swiss events are so popular with the paying
>customers.

Richard Hills:

Umm.  My experience of variable strength opponents in
Canberra-region country congress Swiss teams is that the
luck factor is _not_ huge.  My top-seeded team of
Canberra raiders almost always justifies its seeding by
winning.

Of course, Canberra-region country congress Swiss teams
have six or seven rounds of 8-board matches scored using
the WBF "25" victory point scale.  In ACBL-land seven
rounds of 7-board matches using a primitive win/tie/loss
victory point scale was once popular, and naturally that
sort of victory point scale creates more random results.

And, of course, the hugeness of the luck factor is
directly proportionate to the ratio of number of rounds
versus number of teams.  Six 8-board rounds is adequate
for 30-odd entrants.  Seven 7-board rounds leads to huge
luck for 300-odd entrants.

Robert Geller:

>Given this randomness and uncertainty it seems out of
>proportion to worry about making minuscule adjustments
>in the imp or vp scales that would make them slightly
>more optimum (in a statistical sense) when the
>improvement is probably one significant digit or more
>below the inherent "noise level" anyway.

Richard Hills:

With that I agree.  Even in a "balanced" multiple teams
event, a double round-robin, there are minuscule changes
between using a "one imp = 1 vp" (with upper and lower
limits) or using the WBF "25" victory point scale.  I
once went to the trouble of such a comparative rescoring
of the Aussie Interstate Teams qualifying to find zero
difference in the finishing order of the eight teams
involved in that double round-robin of 20-board matches.

The big advantage of the Aussie Interstate imp=vp scale,
or the Canberra fractional vp scale, is psychological.

It is psychologically more satisfying to instantly know
that you have failed to qualify by 0.75 vp than it is to
wait on tenterhooks, then discover a loss by an arcane
tiebreak rule.


Best wishes

Richard James Hills, amicus curiae
National Training Branch, DIAC
02 6223 9052

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