﻿ Formula Reference > Spreadsheet Formula Functions > POISSON

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:

The Poisson probability mass function is calculated as follows:

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