PlanetMath (more info)
 Math for the people, by the people.
Encyclopedia | Requests | Forums | Docs | Wiki | Random | RSS  
Login
create new user
name:
pass:
forget your password?
Main Menu
Owner confidence rating: Very high Entry average rating: No information on entry rating
Poisson process (Definition)

A counting process $ \lbrace X(t)\mid t\in\mathbb{R}^{+}\cup\lbrace0\rbrace\rbrace$ is called a simple Poisson, or simply a Poisson process with parameter $ \lambda$, also known as the intensity, if

  1. $ X(0)=0$,
  2. $ \lbrace X(t)\rbrace$ has stationary independent increments,
  3. $ P(X(t)=1)=\lambda t+o(t)$,
  4. $ P(X(t)>1)=o(t)$,
where $ o(t)$ is the O notation.

Remarks.

  • The intensity $ \lambda$ is assumed to be a constant in terms of $ t$.
  • Condition 3 above says that the rate in which the an event occurs once in time interval $ t$, as $ t$ approaches 0, is $ \lambda$. Condition 4 says that the event occurs more than once is very unlikely (the rate approaches zero as the time interval shrinks to zero).
  • It can be shown that $ X(t)$ has a Poisson distribution (hence the name of the stochastic process) with parameter $ \lambda t$:
    $\displaystyle P(X(t)=n)=e^{-\lambda t}\frac{{(\lambda t)}^n}{n!}.$
  • Therefore, $ \operatorname{E}[X(t)]=\lambda t$.



Anyone with an account can edit this entry. Please help improve it!

"Poisson process" is owned by CWoo. [ full author list (2) ]
(view preamble)

View style:

Other names:  homogeneous Poisson process
Also defines:  simple Poisson process, intensity
Log in to rate this entry.
(view current ratings)

Cross-references: stochastic process, Poisson distribution, interval, event, terms, O notation, stationary independent increments, parameter, counting process
There are 5 references to this entry.

This is version 5 of Poisson process, born on 2005-02-09, modified 2006-10-04.
Object id is 6733, canonical name is PoissonProcess.
Accessed 8069 times total.

Classification:
AMS MSC60G51 (Probability theory and stochastic processes :: Stochastic processes :: Processes with independent increments)

Pending Errata and Addenda
None.
Discussion
Style: Expand: Order:
forum policy

No messages.

Interact
post | correct | update request | add derivation | add example | add (any)