# NGS on BBO Events

How is the NGS worked out if the Event is a Mitchell?

A pure 2-winner Mitchell is assumed to be 100% accurate since NS are competing against other North Souths.

BUT that is only the case if the number of rounds equals the number of tables - which for normal face-to face is the rule - and why the EBU have the 70% rule to cater for different boards.

BUT on BBO the problem is not the differing boards, it is the difference in the players! If we assume 1 board a round and 1 matchpoint a board then: -

Suppose we have an incomplete Mitchell: Well when NS play EW they are not competing for (R-1) matchpoints - which they would if the board was played R times - they are competing for (T-1) matchpoints since the board is being played at T tables.

But in co-operation they are still co-operating for R-1 matchpoints (Usually 5)

Now if R and T are close together e.g. nine rounds at a ten table event, there is not much competition and the net competition is very small, but if T>>R then the level of competition is quite large. e.g. 32 tables the level of competition is 26 whereas the level of competition between each NS pair is 31

In a wide ranging field - is the potential difference in SOpps significant? I suspect the worst case scenario is when there is something like 12-15 tables when there are six rounds.

Does the NGS algorithm take this into account?

## Comments

As far as I know the NGS does not make any allowance for this.