POISSON.DIST

POISSON.DIST is a DAX function that returns the Poisson distribution for a given number of events over a specific time period.

Syntax

POISSON.DIST(
   X,
   Mean,
   Cumulative
)

Argument	Properties	Description
X		The number of events.
Mean		The expected numeric value.
Cumulative		A logical value that determines the form of the probability distribution returned. If cumulative is TRUE, POISSON.DIST returns the cumulative Poisson probability that the number of random events occurring will be between zero and x inclusive; if FALSE, it returns the Poisson probability mass function that the number of events occurring will be exactly x.

Return Values

Returns the Poisson distribution.

Remarks

• If x is not an integer, it is rounded.

• If x or mean is nonnumeric, POISSON.DIST returns the #VALUE! error value.

• If x < 0, POISSON.DIST returns the #NUM! error value.

• If mean < 0, POISSON.DIST returns the #NUM! error value.

• POISSON.DIST is calculated as follows.

  • For cumulative = FALSE:

    $$\text{POISSON}=\frac{e^{-\lambda }{\lambda }^x}{x!}$$

  • For cumulative = TRUE:

    $$\text{CUMPOISSON}=\sum _{k=0}^x\frac{e^{-\lambda }{\lambda }^x}{k!}$$

• This function is not supported for use in DirectQuery mode when used in calculated columns or row-level security (RLS) rules.

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Contribute » | Contributors: Rick de Groot
Microsoft documentation: https://learn.microsoft.com/en-us/dax/poisson-dist-function-dax