Look at 37%, then take the first good one

Some decisions come one option at a time, with no going back: the flat you let slip gets rented, the candidate you turn down accepts another offer. How long do you look before you decide? Choose early and something better may have been coming; wait too long and the best has already gone by.

Mathematicians have studied this problem for decades and the answer is surprisingly precise: 37%. The optimal strategy splits the search into two phases. For the first 37% of the options (or of the time you've given yourself) you only look: you commit to nothing, you simply calibrate the level. From then on, you take the first option that beats everything you've seen.

It doesn't guarantee the best outcome — nothing does — but it can be proven that no other proportion does better: explore less and you decide blind, explore more and you let the good ones pass.

The useful part isn't the exact figure, it's what it does to your head: it turns the anxiety of "what if there's something better?" into a deadline. If you give yourself a month to find a flat, the first eleven days are for looking around calmly. After that, the first one that makes you raise an eyebrow: that one.