January 28, 2013

More lottery nonsense

From Stuff, on this week’s Lotto

The winner chose the six lucky numbers they played regularly but, in a clever move, chose to play the same numbers on 10 different lines with each Powerball number. That way they were ensured to win Powerball if their lucky numbers came up.

This strategy doesn’t increase the chance of winning Powerball, because you can’t increase the chance except by cheating or magic.   If they match the six numbers they are certain to win Powerball, rather than having only a 10% chance, but this is exactly compensated by their ten-fold lower chance of having a ticket that matches all six numbers.

The strategy does reduce the chance of winning the first division, by a factor of ten, but increases the fraction of the first-division prize that they snag (in this particular win, from 1/4 to 10/13). Over all, the strategy reduces expected winnings compared to ten random picks. On the other hand, if you cared primarily about average expected return you wouldn’t be playing Lotto.

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar
    Martin Kealey

    When my wife is feeling unwell, I find myself despatched to the local Lotto outlet to get her a ticket.

    So far I haven’t been able to convince her to let me put the money in a box and pull it out again when her numbers would win a prize. I figure it’s an excellent deal, since on average this would increase her winnings by about 90%, but she seems unconvinced.

    12 years ago

    • avatar

      Have you considered doing both? Buy the tickets, but also put the money away – that way she doesn’t have the risk, so might go along with it.

      12 years ago

  • avatar
    Thomas Lumley

    I should perhaps note the unofficial position of this blog on the lottery:

    Lots of people enjoy playing the lottery, and it’s unfortunate that this relatively harmless and fairly inexpensive entertainment causes so many really bad news stories.

    12 years ago