Propects Look Bleak

10 Sep

Discussion of today’s XKCD comic in the XKCD forums led me to a calculation of the probability of finding a girlfriend written by Tristan Miller. The argument is a fun look at the mathematical basis for why coupling can be so hit-or-miss. Most of the steps in his argument make sense except the conclusion… I don’t think it’s correct to assume that it would take ~3400 blind dates to find a suitable mate, in the same way that it doesn’t take 365 random people to find two with the same birthday (please correct me if I’m wrong here).

Interlocked Hearts


Posted by on September 10, 2007 in Entertainment, Garbage In, Garbage Out



3 responses to “Propects Look Bleak

  1. weirleader

    September 14, 2007 at 12:14 am

    Unfortunately, I don’t think the situation of finding two people with the same birthday quite applies here – because more people mean more chance that SOMEBODY has matching birthdays, but not necessarily YOUR birthday. In the case of finding a girlfriend, we’re more interested in yours truly finding the girlfriend as opposed to some random guy out there.

    But! There is one addition I’d like to make to his calculations… His probability was based on randomly dating all women his age. If he restricts himself (as he suggested he would) to only those who are available, he suggests that cuts the pool in half, which should essentially double his chances.

    Additionally, his calculation of ~3400 blind dates (which I think we could reduce to ~1700) is an average time until Ms. Perfect is found… there’s still a pretty good chance of finding Ms. Perfect after only 800 or so… there’s even more I could add, but I sense I’m starting to ramble.

  2. halfawake

    September 14, 2007 at 1:52 am

    Good point about my error on the birthday thing weirleader! I think the problem I had was just that “I would have to date for 3493 weeks before I found one of the 18 726″ implies that 3493 weeks would be necessary, when, as you point out, it’s actually an average.

    It would be nice to see a calculation of how many people you would need in a room to have a 50% chance that two of them are a good match. This would have implications for speed dating, etc. :-).

    I don’t know if this is part of the “even more you could add”, but it just occured to me that you could do a cool time-varying version of them where the size of the dating pool varies as you age (thereby incorporating the stuff in the XKCD comic. You’d have to do some kind of integration I think.


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