Dear Economist

How long to wait for the perfect espresso?

Dear Economist,
I just popped out of my office to grab a coffee from the best local place, a minute’s walk away. When I got there I found a sign saying “Back in ten mins”. It’s quite cold, and since I hadn’t expected to be out for more than a few minutes, I’m not wearing a coat. There are several alternative coffee vendors close by, some of which experience shows produce bad coffee, and some of which are untried, but don’t normally have a queue that suggests greatness. There’s nothing useful to do while I wait.
How long should I have waited before defecting to an alternative vendor?
Yours Sincerely,
-Tom
Dear Tom,
Let’s get the maths out of the way first. If the barista really knew he would be absent for 10 minutes when putting up the sign, you’re equally likely to have arrived just after he leaves, or just before he returns. You’d expect to wait five minutes on average.
The barista may have been cleverer than that, however: knowing that most customers would not arrive immediately after he skived off, he might have given himself extra slack. Perhaps he plans to be absent for twenty minutes, leaving your expected wait at an unacceptable ten.
These seem to be your regular haunts, so in future I advise that you immediately try somewhere else. If the coffee is better – even if that is unlikely – that knowledge will be something you can use every day. If not, at least you will have kept warm.
And if you do decide to stand and wait, make sure you try for a free coffee when the absent proprietor returns.

First published in “Mens Health”

5th of May, 2011Dear Economist • Comments off