| Poisson Distribution |
|---|
When n is large, the calculation of binomial probabilities according to their formula will usually involve a prohibitive amount of work.
A random variable X has a Poisson distribution and it is referred to as a Poisson random variable if and only if its probability distribution is given by
R has four dedicated commands for density, distribution function, quantile
function, and random generation for the Poisson distribution with parameters
\[
P(x; \lambda ) = \frac{\lambda^x}{x!} \,e^{-\lambda} \qquad
\mbox{ for } \ x=0,1,2,\ldots .
\]
size and prob:
- dpois(x, lambda, log = FALSE)
- ppois(q, lambda, lower.tail = TRUE, log.p = FALSE)
- qpois(p, lambda, lower.tail = TRUE, log.p = FALSE)
- rpois(n, lambda)