The old ACF Bulletin Board has previously debated the merits and demerits of 'junk' rounds in SWISS tournaments.
Junk rounds have the drawback of discouraging stronger players from entering all-in SWISS tournaments.
Strong players are more likely to be attracted to those SWISS tournaments where modification is made to the structure such as holding a Championship and Reserves. In this way the effect of junk games is reduced by separating the field into two distinct tournaments. However, the separation of the B-quartile from the top players creates its own resentment in the underclass. You only have to read the vigorous debate in firegoats “Championship qualifier criteria” to see that B-quartile players like to have the chance to play against
quartile players.
So this is the dilemma for the tournament designer: how to create a pairings arrangement that pairs players of comparable ratings without going to the extreme of shunting the B-quartile and
quartile players into a separate tournament.
Box Hill Chess Club experimented for a couple of years with a permanent acceleration (of 2 bonus points) for the A division players in a large all-in SWISS.
These SWISSes have mainly been 7-evening events at (about) 90 minute time controls for 80-100 players.
The all-in field is split into 2 divisions. Prizes are available in each division; but the bottom division players cannot win a top division prize is set as a tournament condition.
There are two benefits of this system
1) Junk games are reduced dramatically.
2) Prizes for
quartile winners (that is the top players in the bottom division) are much fairer as these players are scoring 5 points out of 7 instead of 3 out of 7 in a normal SWISS. Fluke results and cinchy pairings are reduced in their effect on the prizes.
While debate on the merits of these various tournament formats has been spirited, we lacked a measure of the relative competitiveness of various tournament formats. The design of events is a major influence on whether players are attracted to the event. (The other major factor is obviously the rewards by way of prizes and titles).
After further BB debate it emerged that the metric that serves the purpose of measuring competitiveness is the calculation of the mean of absolute differences of ratings for all pairings. This is calculated on a round by round basis.
Who knows...one day we might be able to advertise a tournament as
“Guaranteed for this tournament the mean of absolute differences of ratings for all pairings is less than 200” and this could attract strong players. Implicitly this is why Victorian INTERCLUB was always so attractive at the A grade level. It had a very low mean of absolute differences of ratings for all pairings.
Edit
This post has appeared on three bbs to date. Cut-and-pasted here with a few minor edits.
Curiously the Ozchess software treats (A -) as a smilies, and C - also.
I left them in the text because they became rather appropriate anyway.
<Original version is here>