# POISSON

POISSON(x, mean, cumulative)

Returns the probability distribution function OR the cumulative probability function for a poisson distribution.

 x The number of events. mean The expected numeric value. cumulative A logical value indicating the type of function to use:False (or 0) = [[probability distribution function]] (equal to)True (<> 0) = [[cumulative probability function]] (equal to or less than)

 REMARKS
 * POISSON.DIST was added in Excel 2010 to replace this function.* The poisson distribution is a [[discrete distribution]]* If "x" is not an integer, it is truncated.* If "x" is not numeric, then #VALUE! is returned.* If "mean" is not numeric, then #VALUE! is returned.* If "mean" = 0, then #NUM! is returned.* If "x" < 0, then #NUM! is returned.* If "x" = 0, then* If "cumulative" = False, then the height of the curve at "x" is returned.* If "cumulative" = True, then the area under the curve to the left of "x" is returned.* For the Microsoft documentation refer to support.microsoft.com

 A 1 =POISSON(2, 5, FALSE) = 0.084 2 =POISSON(2, 5, TRUE) = 0.125 3 =POISSON(2, 2, 1) = 0.677 4 =POISSON(-2, 2, 1) = #NUM!