The POISSON.DIST function returns the Poisson distribution. A common application of the Poisson distribution is predicting the number of events over a specific time, such as the number of cars arriving at a toll plaza in 1 minute.
- This function was introduced in Excel 2010 and so is not available in earlier versions.
- The POISSON.DIST function replaces the POISSON function included in earlier versions of Excel.
|x||The number of events – must be ≥ 0|
|mean||The expected number of events – must be ≥ 0|
|cumulative||A logical value that determines the form of the probability distribution returned
|6||=POISSON.DIST(A2,A3,TRUE)||0.010336||Cumulative Poisson probability with the arguments specified in A2 and A3|
|7||=POISSON.DIST(A2,A3,FALSE)||0.007567||Poisson probability mass function with the arguments specified in A2 and A3|
Common Function Error(s)
|Problem||What went wrong|
|#VALUE!||Occurs if either of the supplied x or mean arguments are non-numeric|
|#NUM!||Occurs if either of the supplied x or mean arguments are < 0|
The Poisson distribution is a discrete probability function that can be used to find the probability of a number of events occurring in a specified time period.
The probability mass function shows the probability of exactly x occurrences, and is calculated as:
where is the expected number of occurrences within the specified time period.
The cumulative distribution functions shows the probability of at most x occurrences, and is calculated as:
See Wikipedia for more information on poisson distribution.