Poisson Distribution

Overview

  • The Poisson distribution models the number of events occurring in a fixed interval of time or space, given that these events occur with a constant rate and are independent of the time since the last event.
  • It is often used to model rare events or phenomena where the probability of occurrence is small over a specific interval.

Use Case

  • Used in various fields such as insurance (to model the number of claims per day), telecommunications (to model the number of phone calls arriving at a call center), and biology (to model the number of mutations in a DNA sequence).

Formula

  • Probability Mass Function (PMF):
    • : Number of events occurring in the interval
    • : Average rate of events occurring in the interval (also known as the rate parameter)
    • : Euler's number, approximately equal to 2.71828

Example

  • Call Center:
    • Suppose a call center receives on average 10 calls per hour .
    • We want to find the probability of receiving exactly 5 calls in the next hour .
    • Using the Poisson PMF: