Interarrival time

Topic of Poisson processes, part of Stochastic processes

Interarrival time

Type Topic
Taught in Poisson processes
Part Stochastic processes

The wait W_n=T_n-T_{n-1} between successive events of a counting process. For a homogeneous Poisson process of rate \lambda the interarrival times are independent exponentials with mean 1/\lambda, and the arrival times T_n are their partial sums; the converse construction gives a Poisson process too.

In Poisson processes

T_1 is exponential with rate \lambda, in the parameterisation on the distribution sheet: density \lambda e^{-\lambda t} on (0,\infty), mean 1/\lambda. Independent increments make the later interarrival times W_1,W_2,\ldots independent copies of that exponential law. The arrival times are the partial sums T_n=\sum_{i=1}^n W_i. The construction runs in reverse as well. Independent exponential interarrival times of rate \lambda produce a Poisson process of rate \lambda.

Used in

See also

Event · Homogeneous Poisson process · Forward equations of the Poisson process · Nonhomogeneous Poisson process · Superposition and thinning · Spatial Poisson process · Intensity function

Glossary and index