DIDO, or...  Drop In, Drop Out

A method of running duplicate bridge events without...

• Everybody being there at the Start
• Everybody being there at the End
• Any time pressure!

I find it invaluable both for non-serious holiday events, and for introducing learners to duplicate events (because of the lack of time pressure).

It is not intended to be a replacement for standard duplicate movements!

One of the interesting things about it is that it cuts waiting (non-playing) time in half.

Methodology

The way it works is this:

• Every pair that arrives goes in to a queue
• Whenever there's 2 pairs in the queue that have not yet played each other, and an available set of boards that neither have played, then they take those boards to a vacant table and play them.
• Once they have completed them, the boards become available again and the pairs go back into the queue (at the end)

Pairs are allocated by:

• Starting with the first pair in the queue, check whether they can play the second pair.
• If not check if the first pair against the third pair etc. 
• If the first pair can't play anyone in the queue, start again with the second pair and so on.
• If no-one can be paired, wait until new pairs join the queue.
• Once you have matched two pairs, start again from the front of the queue.

Boards sets are also in a queue, with those returned going to the back of the queue.  This ensures boards are played approximately the same number of times, and that we aren't held up waiting for boards later on.

In practice, this means:

With an odd number of pairs:

• There will be a sitting out pair.
• When a table is up, one pair from that table plays with the sitting out pair (if possible).
• I usually swivel them to make it fair (so when a table is up, EW swivel to NS, and NS become the sitting out pair).

With an even number of pairs:

When two tables are up, swap so that pairs play a pair they have not yet played.

There's nothing in principle that stops pairs playing each other more than once (like a revenge round).  For introducing learners to duplicate scoring you could, for example, play an entire duplicate event without anyone moving.

Does it Work?

Yes.  I have run DIDO events 6 times now, ánd they work very well. 

So why use it?

Benefits

• Pairs can arrive after the start of the event and still partake
• Pairs can leave before the end without disrupting the play
• Pairs can take a break (e.g. for tea/coffee) without disrupting the play
• No time pressure
• Waiting (non-playing) time is cut from 23% for "normal" duplicate pairs to just 10%

Disadvantages

• It (currently) has to be scored by hand (I'm working on that!)
• Waits can get long if it gets down to less than 10 pairs
• You need about 10% more boards compared to a standard duplicate movement for the same number of pairs
• Thus boards are played 10% less on average

Jeremy

07969 297 633

06/04/2026