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Formula Functions / Functions M to Q / POISSON
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    POISSON
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    This function returns the Poisson distribution.

    Syntax

    POISSON(nevents,mean,cumulative)

    Remarks

    This function has these arguments:

    Argument Description
    nevents Number of events Provide an integer, or the value is truncated. The number must be greater than zero.
    mean Expected numeric value The number must be greater than zero.
    cumulative Set to TRUE to return the cumulative Poisson probability that the number of random events occurring is between zero and nevents inclusive. Set to FALSE to return the Poisson probability mass function that the number of events occurring is exactly nevents.

    Remarks

    The cumulative Poisson probability is calculated as follows:

    Cumulative Poisson Probability Equation

    The Poisson probability mass function is calculated as follows:

    Poisson probability mass function

    where x is the number of events (nevents argument), mu is the mean (mean argument).

    Data Types

    Accepts numeric data for all arguments. Returns numeric data.

    Examples

    POISSON(A3,B4,TRUE)

    POISSON(R1C2,3,FALSE)

    POISSON(7,4,TRUE) gives the result 0.948866384

    POISSON(7,4,FALSE) gives the result 0.059540363

    Version Available

    This function is available in product version 1.0 or later.

    See Also

    BINOMDIST | GAMMADIST | HYPGEOMDIST | Statistical Functions