I know arrow switching to achieve a one winner result is optimal at 1 in 8. Is there a guide for higher numbers of tables/movements and does it matter which rounds are arrow switched?
Cheers, Nick
It does matter which rounds but not very much. There is so much "noise" that as long as you do something close to optimal there is little point in worrying. We say to arrow switch the last round of up to 9 rounds and the last two rounds of 12 or more.
Optimal arrow switching systems tend to be very complex (e.g. switching some boards on a round, but not others, distributed over several rounds) and the gain from them is sufficiently minimal that it's more likely to cause less reliable results through player error than it is to cause more reliable results through the slight increase in competition.
The "switch approximately 1 in 8 of the rounds" guideline is an approximation of the perfect schedule that's easy to remember and likely to work as well in practice as anything else you might come up with, assuming your goal with the arrow-switching is to put N/S and E/W players on a level footing. Switching the first ⅛ or last ⅛ of the rounds are equivalent, so you can do whichever makes more sense in the movement.
There are three main aims you could have in a movement:
One competition between N/S players, a second, independent competition between E/W players ("two winner movement"): in a Mitchell-alike, switch no rounds
One competition that ranks N/S players and E/W players equally ("one winner movement"): in a Mitchell-alike, switch approximately ⅛ of the rounds
A competition between the "N/S team" and the "E/W team" (i.e. you want to maximise competition between players in opposite directions, and minimize competition between players in the same direction, the opposite of a two-winner movement, and a sort of generalisation of "teams of 8" to arbitrarily large teams): I believe this involves arrow switching more than ⅛ of the rounds, but do not know the exact number (it's probably either ¼ or ½)
Actually, now I've written that, I'm curious as to whether there are any "theoretically perfect" arrow-switching schedules which, despite being complex, at least form enough of a pattern to be relatively easy for a TD to remember. Perhaps it's only possible at certain numbers of tables?
I used to always switch on the last one or two rounds, however, this leaves a problem if you need to skip the last round of play. So, I think it would be easier to switch the first one or two rounds, so that the last round becomes more optional on the night, without compromising the competitiveness.
For example, our Wednesday night has a hard cutoff of 22:15, which normally allows time for 24-27 boards. If we are aiming for 27 boards but need to skip the last round (or a board or two from the last round) to ensure that we end on time, then switching early makes a lot of sense.
I am yet to try this, but will aim to switch on 1 or 2 rounds at the start - 1 for up to 8 rounds and 2 for 9+.
With an arrow switch on the final round you can shorten a long session by not playing the penultimate round.
It's a bit messy with BridgeMate where you may need the Director to mark all boards of the round Not Played but I suspect it is less confusing for the players than arrow switching Round 1.
Comments
Which sort of leaves a gap in 10 and 11. I suppose playing a hesitation Mitchell counts as one switch.
Hesitation Mitchell does its own arrow switches automatically.
Alan
Optimal arrow switching systems tend to be very complex (e.g. switching some boards on a round, but not others, distributed over several rounds) and the gain from them is sufficiently minimal that it's more likely to cause less reliable results through player error than it is to cause more reliable results through the slight increase in competition.
The "switch approximately 1 in 8 of the rounds" guideline is an approximation of the perfect schedule that's easy to remember and likely to work as well in practice as anything else you might come up with, assuming your goal with the arrow-switching is to put N/S and E/W players on a level footing. Switching the first ⅛ or last ⅛ of the rounds are equivalent, so you can do whichever makes more sense in the movement.
There are three main aims you could have in a movement:
Actually, now I've written that, I'm curious as to whether there are any "theoretically perfect" arrow-switching schedules which, despite being complex, at least form enough of a pattern to be relatively easy for a TD to remember. Perhaps it's only possible at certain numbers of tables?
I used to always switch on the last one or two rounds, however, this leaves a problem if you need to skip the last round of play. So, I think it would be easier to switch the first one or two rounds, so that the last round becomes more optional on the night, without compromising the competitiveness.
For example, our Wednesday night has a hard cutoff of 22:15, which normally allows time for 24-27 boards. If we are aiming for 27 boards but need to skip the last round (or a board or two from the last round) to ensure that we end on time, then switching early makes a lot of sense.
I am yet to try this, but will aim to switch on 1 or 2 rounds at the start - 1 for up to 8 rounds and 2 for 9+.
With an arrow switch on the final round you can shorten a long session by not playing the penultimate round.
It's a bit messy with BridgeMate where you may need the Director to mark all boards of the round Not Played but I suspect it is less confusing for the players than arrow switching Round 1.
Alan