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Math Help - Formula to find cumulative probability from z-score

  1. #1
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    Formula to find cumulative probability from z-score

    I want a formula to calculate the cumulative normal probability from a given z-score. e.g. f(1) = 0.3413, but I can live with f(0.3413) = 1
    I don't want to use a table.
    I don't know or want to learn integral calculus for this, but I can use a Basic iterative program loop if required.
    I used to have a calculator (radio shack EC-4004 circa 1988) that provided a formula to approximate the value as a sample program, but the manual is lost and I can't even remember the name of the mathematician credited for the formula.
    Thanks for any help.
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  2. #2
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    It sounds like you already know there is no exact formula in a closed form. There are some approximations here:

    http://en.wikipedia.org/wiki/Normal_...the_normal_CDF


    Wikipedia is not the most reliable source in the world so you may want to independantly verify whatever formula you choose to use.
    Last edited by SpringFan25; March 29th 2011 at 12:19 PM.
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  3. #3
    MHF Contributor matheagle's Avatar
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    I was going to show you how simple Taylor Series is here
    But you don't want to see it
    that's a shame
    Last edited by matheagle; March 29th 2011 at 04:54 PM.
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  4. #4
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    I have to say I find this article useless. I guess it's over my head.
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