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The formula for NORMSDIST is wrong?

  1. #1
    SyBorg
    Guest

    The formula for NORMSDIST is wrong?

    nI tried using the equation from the help menu to verify NORMSDIST(1.3333),
    as follows:

    (EXP(-POWER(1.3333,2)/2))/SQRT(2*PI())

    but I don't get the same answer. Instead, I get 0.164017.

    What am I doing wrong?

  2. #2
    Bernard Liengme
    Guest

    Re: The formula for NORMSDIST is wrong?

    normSdist always returns the cumulative value (ie the area under the curve
    up to value of z)
    normdist lets you choose cumulative or not.
    Also the first is set for mean = 0, stdev=1 while the second allows you to
    specify these values.
    The formula =NORMDIST(1.3333,0,1,0) returns 0.164017 since the last argument
    of 0 specifies non-cumulative.
    best wishes
    --
    Bernard V Liengme
    www.stfx.ca/people/bliengme
    remove caps from email

    "SyBorg" <SyBorg@discussions.microsoft.com> wrote in message
    news:ADFA0946-2708-405F-A99D-B798FE2DE653@microsoft.com...
    > nI tried using the equation from the help menu to verify
    > NORMSDIST(1.3333),
    > as follows:
    >
    > (EXP(-POWER(1.3333,2)/2))/SQRT(2*PI())
    >
    > but I don't get the same answer. Instead, I get 0.164017.
    >
    > What am I doing wrong?




  3. #3
    David Biddulph
    Guest

    Re: The formula for NORMSDIST is wrong?

    "SyBorg" <SyBorg@discussions.microsoft.com> wrote in message
    news:ADFA0946-2708-405F-A99D-B798FE2DE653@microsoft.com...
    > nI tried using the equation from the help menu to verify
    > NORMSDIST(1.3333),
    > as follows:
    >
    > (EXP(-POWER(1.3333,2)/2))/SQRT(2*PI())
    >
    > but I don't get the same answer. Instead, I get 0.164017.
    >
    > What am I doing wrong?


    Doesn't the help say that NORMSDIST is the *cumulative* function, whereas
    the (EXP(-POWER(z,2)/2))/SQRT(2*PI()) is the *density* function?
    Plot each against z.
    Integrate the density from z = - infinity and compare that with the
    cumulative.
    --
    David Biddulph



  4. #4
    Registered User
    Join Date
    04-07-2011
    Location
    Maine, USA
    MS-Off Ver
    Excel 2003
    Posts
    1

    Re: The formula for NORMSDIST is wrong?

    David Biddulph - Thank you. Although I read the excel help on this function many times trying to figure out the same problem as SyBorg, I failed to read it carefully enough. It doesn't help that the monograph I was following incorrectly equated NORMSDIST with the density function.

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