midProbability
What is Poisson distribution and when is it used?
Updated May 17, 2026
Short answer
Poisson distribution models number of events in a fixed interval of time or space.
Deep explanation
It assumes events occur independently with constant average rate λ. It is widely used for rare event modeling.
Real-world example
Number of customer arrivals per minute.
Common mistakes
- Confusing Poisson with binomial in small samples.
Follow-up questions
- What is lambda in Poisson?
- When does Poisson approximate binomial?