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probability math

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  • pentatonika2000
    I recently read about an astrologer who was asked to write horoscopes for 12 unidentified people, meet those 12 people, and then guess which was which. The
    Message 1 of 2 , Feb 8, 2002
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      I recently read about an astrologer who was asked to write horoscopes
      for 12 unidentified people, meet those 12 people, and then guess
      which was which.
      The astrologer didn't make a single correct guess.

      That surprised me, because I thought that the chances were greater
      than 50% in favor of getting at least one correct guess.

      But I think I was wrong. I began calculating the formula for the
      chances of getting at least one correct match given the number of
      people being matched. Here's what I came up with:

      Given 1 person, the chances are 1 out of 1.
      Given 2 persons, the chances are 1 out of 2.
      Given 3 persons, the chances are 4 out of 6.
      Given 4 persons, the chances are 6 out of 16.

      And that's as far as I figured.
      I can't discern a pattern from this data, and it would be quite
      laborious to figure out the chances given 5 persons.
      Does anything already know what the formula is?
      Or does anything see a formula from this data?
      If so, please write back.

      Thomas Robertson
      http://www.pentatonika.com
    • eric
      Thomas, actually some paranormalists have tried to get credit for reverse hits when they appear to get far below normal chance. It utterly amazes me that so
      Message 2 of 2 , Feb 9, 2002
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        Thomas,

        actually some paranormalists have tried to get credit for "reverse hits" when they
        appear to get far below normal chance. It utterly amazes me that so many people
        believe in astrology when it is so simple to disprove. Culver and Ianna wrote the
        one of the only good (read skeptical) book on astrology out there.

        I'm bcc-ing a high school student who has some interest in taking on a
        senior project to investigate paranormal claims. I personally think the math
        of looking for above chance probabilities of hits could be fascinating.
        Probability does sometimes appear to violate ones intuitive sense. If I were
        testing astrology, I'd probably try to have people pick which of only 4 charts
        were heir's. I'd also take care to try to filter out subjects who already closely
        followed their charts. Realize that if you disproved one astrologer, others would
        say you used the wrong method. I offer a lot more ramblings on astrology at:
        http://www.phact.org/e/astrolgy.htm

        Eric Krieg
        ----- Original Message -----
        From: "pentatonika2000" <pentatonika@...>
        To: <skeptical@yahoogroups.com>
        Sent: Saturday, February 09, 2002 1:54 AM
        Subject: [skeptical] probability math


        >
        > I recently read about an astrologer who was asked to write horoscopes
        > for 12 unidentified people, meet those 12 people, and then guess
        > which was which.
        > The astrologer didn't make a single correct guess.
        >
        > That surprised me, because I thought that the chances were greater
        > than 50% in favor of getting at least one correct guess.
        >
        > But I think I was wrong. I began calculating the formula for the
        > chances of getting at least one correct match given the number of
        > people being matched. Here's what I came up with:
        >
        > Given 1 person, the chances are 1 out of 1.
        > Given 2 persons, the chances are 1 out of 2.
        > Given 3 persons, the chances are 4 out of 6.
        > Given 4 persons, the chances are 6 out of 16.
        >
        > And that's as far as I figured.
        > I can't discern a pattern from this data, and it would be quite
        > laborious to figure out the chances given 5 persons.
        > Does anything already know what the formula is?
        > Or does anything see a formula from this data?
        > If so, please write back.
        >
        > Thomas Robertson
        > http://www.pentatonika.com
        >
        >
        >
        >
        >
        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
        >
        >
        >
        >
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