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Probabilty of sequential deaths

  1. Oct 27, 2006 #1
    Hi all,

    I hope today finds you well and in good spirits.

    I'm trying to develope a statistical model and haven't done so in years. Any help is appreciated.

    The Birthday problem goes something like this:

    The question is:-

    "How many people should be gathered in a room together before it is more likely than not that two of them share the same birthday?"

    The compound probability of birthday 2 being different from birthday 1, and of birthday 3 being different from the other two, these being independent outcomes, is:-

    (364/365)*(363/365) = 0.991796 or 99.2% chance that two people will not share the same birthday.

    My question goes something like this:

    My question is what are the odds of blood relatives dying on a personally or globally significant date (See below).

    We observe two calendars in the family, Gregorian (Greek Orthodox) for religious purposes, and Julian (standard).

    Helene, Jean, and Xenia are my aunts. Estelle and Edward are my mother and father.

    ****Name*****Birth *******Death**Age*Date Sign.*Calendar
    1999 Helene--01 Oct 1911--09 Jan 1999-88-Christmas---Gregorian

    2000 Jean*---07 Sep 1913--26 Dec 2000-87-Christmas--Julian

    2001 Estelle--31 May 1925--28 Dec 2001-76-Christmas--Julian

    2002 None

    2003 None

    2004 None

    2005 Xenia----31 Dec 1917--11 Sep 2005-88-9/11--------Julian

    2006 Edward--15 May 1921--07 Sep 2006-85-Sister Jean--Julian

    At this point I have the U.S. Social Security Period Life Table.

    Discounting for illness, which most of us die from, I'd like to derive the "odds".

    Even pieces of the model would be helpful. Any help is appreciated.

    Best regards,

    Statictically Challenged
  2. jcsd
  3. Oct 27, 2006 #2


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    The problem is that it's easy to find connections after the fact. Assuming a 365-day year with a fixed calendar, the chance that any three given people would die on Christmas is 1/365^3. The chance that exactly three out of five given people would die on Christmas on one of two calendars is roughly 80/365^3. The chance that at least three out of five given people would die on a 'significant day' in one of two calendars is higher yet. The chance that, out of the six billion plus people in the world, at least one would have three or more relatives die on a 'significant day' in one of two calendars is essentially 100%.
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