How do you determine the variance of a Poisson distribution?

1 Answer
Nov 8, 2015

The Poisson Distribution is that of a discrete random variable. Hence we use the summation procedure.

Explanation:

For any random variable X, the variance is defined as

sigma^2 = E(X^2) - [E(X)]^2.
if the random variable is a discrete random variable, we obtain
sigma^2 = sum_0^inftyx^2p(x) - [ sum_0^inftyx.p(x)]^2 where
p(x) =((e^(-mu}mu^x) / (x!)) x = 0,1,2,3,-----infty
Finally, the answer is obtained as mu.