Poisson Distribution

The Poisson distribution (the term first used by Soper, 1914) is defined as:

f(x) = (lx * e-l )/x!

for x = 0,1,2,...; 0 < l

where

l

(lambda) is the expected value of x (the mean)

e

is the base of the natural logarithm, sometimes called Euler's e (2.71...)

For a complete listing of all distribution functions, see Distributions and Their Functions.