The Mathematical Formula For Making Hard Decisions, Like Who To Marry

The Mathematical Formula For Making Hard Decisions, Like Who To Marry

Throughout our lives, we have to make difficult, life-changing decisions, such as which job to take, which job candidate to hire, and who’s worthy of your “til death do us part” vow. You can increase your odds of making a happy choice with this mathematical formula.

Picture: keepitsurreal/Flickr

The dilemma is called “The Marriage Problem” (or “The Secretary Problem”). When you’re dating, for example, how do you know that this person is The One? If you decide to marry him or her, you’ve cut yourself off from all other potential soul mates.

NPR reports on the maths-based strategy to solve this dilemma, developed by Martin Gardner in the 1960s [emphasis mine]:

[Author of The Grapes of Maths, Alex Bellos] writes: “Imagine that you are interviewing 20 people to be your secretary [or your spouse or your garage mechanic] with the rule that you must decide at the end of each interview whether or not to give that applicant the job.” If you offer the job to somebody, game’s up. You can’t go on and meet the others. “If you haven’t chosen anyone by the time you see the last candidate, you must offer the job to her,” Alex writes (not assuming that all secretaries are female — he’s just adapting the attitudes of the early ’60s).

So remember: At the end of each interview, you either make an offer or you move on.

If you don’t make an offer, no going back. Once you make an offer, the game stops.

According to Martin Gardner, who in 1960 described the formula (partly worked out earlier by others), the best way to proceed is to interview (or date) the first 36.8 per cent of the candidates. Don’t hire (or marry) any of them, but as soon as you meet a candidate who’s better than the best of that first group — that’s the one you choose! Yes, the Very Best Candidate might show up in that first 36.8 per cent — in which case you’ll be stuck with second best, but still, if you like favourable odds, this is the best way to go.

Apparently, this 36.8 per cent number has been proven time and again to increase satisfaction. By “trying out” the first 36.8 per cent but not not ending the “game” or search there, you compile a group that you can compare all future people to.

If you have a mind for maths, you can read more about the formula here.

It’s not a foolproof strategy by any means — maybe you fall hopelessly in love with the first person you date — but in other circumstances, when you have multiple options, mathematicians say it’s a better strategy than picking at random.

How to Marry the Right Girl: A Mathematical Solution [NPR]


  • Unfortunately, this has no applicability to dating or marriage, because we don’t know how many total “candidates” there are going to be. So how do we stop at 36.8%?

    • 36.8% of all living single people of the opposite gender on Earth. Better get to work!

  • Or approximate a time window that constitutes a “trying out” and divide the potential time you are willing to spend searching. For example on average I would like to date a potential partner for 4mths and before I marry I have a 5 year time horizon for “trying out” partners, therefore my candidate pool is 15. After trying out 5 partners I choose the next that is better than the best of the 5 (or 6 depending on your rounding pref).

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