Compatibility - POISSON Function

The POISSON function replaces the POISSON.DIST function in Excel 2010.

Description

The function returns the Poisson distribution. A common application of the Poisson distribution is predicting the number of events over a specific time.

Syntax

POISSON(x,mean,cumulative)

Arguments

Argument Description Required/ Optional
X The number of events. Required
Mean The expected numeric value. Required
Cumulative

A logical value that determines the form of the probability distribution returned.

If cumulative is TRUE, POISSON returns the cumulative Poisson probability that the number of random events occurring will be between zero and x inclusive.

If cumulative is FALSE, POISSON returns the Poisson probability mass function that the number of events occurring will be exactly x.

 Required

Notes

  • POISSON is calculated as follows −

    • For cumulative = FALSE,

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

    • For cumulative = TRUE,

      $$CUMPOISSON =\sum_{k=0}^{x} \frac{e^{-\lambda}\lambda^x}{k!}$$

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

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

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

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

Example

POISSON Function
advanced_excel_compatibility_functions.htm
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