I am just back from the G4G conference in Atlanta, where I gave a six-minute talk on how to organize a waiting line. The video of the actual talk will appear on the web eventually, but in the meantime, here is video of my practice run from the night before:
Or, for higher quality video, click here.
A question of practical implementation. How do you prevent a person at the back of the line from leaving the line, and then getting back into the line at the front?
An anecdote from Svetlana Alexievich I found enduringly amusing, so perhaps worth passing along, even if only slightly relevant here…. During the break-up of the Soviet Union, many people wanted to renounce their membership in the Communist Party. They wrote long letters stating their reasons why. Some became disillusioned over time, and lost faith. Others never really believed in it, but felt they needed to join the party simply to get by. They all expect to be able to turn in their membership cards along with the letters they’ve written in some sort of meaningful ceremonial exchange, to signal: I quit. But the nation is in such turmoil, there are very few remaining party members showing up for work at the office to allow that. So what happens? Long queues form, and people dutifully wait in line for hours.
I’m thinking about an actual scenario in which a basketball team has of 10 has been practicing hard, and the coach calls a break to allow them to get a drink. They are all equally parched. The coach commands that if a line forms, any newcomer to the line goes to the front.
If I were a player, and someone else raced to the fountain to get a drink ahead of me, I would probably be willing to wait behind him to take my turn. Maybe a couple of others would as well (the “Goldilocks” line). But might the rest realize that rather than wait in line, they can simply declare themselves newcomers, and go to the front? If so, who qualifies as he next newcomer? I must be missing something. Or maybe my example misses the mark because the fountain has suddenly been made available, versus the one in the park you describe.
Chad asked the same thing I did, but far more succinctly. So an explanation would be a two-for-one.
Chad and JB:
Apologies for the delay; somehow WordPress stopped sending me notifications of new comments.
You absolutely have to include (and somehow enforce) a prohibition against leaving the line and re-entering.
If that sounds impractical for water fountains, it works better for phone queues. You call Microsoft for technical assistance. A recording tells you that you’re at the front of the line but will be pushed back by each newcomer. You get periodic updates along the lines of “You are now twelfth in line”. And if you hang up and call again from the same number, your call is blocked. (Of course we still have to prevent you from using a different phone.)
An alternative is to send newcomers not to the first place, but to the next-to-last place (while prohibiting leaving and re-entering). That also achieves the optimal line length, for exactly the same reason — and makes it easier to catch cheaters, because if John is last and Chad is next-to-last, and John leaves the line and re-enters in front of Chad, I bet Chad will notice — and can employ any of the methods that we currently employ to intimidate people out of cutting into lines.
I am persuaded that from a practical point of view, it can work in some places, like the aforementioned customer call center. But if that is the case, is this truly a commonly applied queue system? If not, why not?