Poisson probability
Find the probability of a count over a fixed interval.
How this works
P(X=k) = e⁻λ λᵏ/k!. Assumes independent events and a constant mean rate.
Example
Using the example inputs, probability is 0.2240418077.
- Expected count in interval
- 3
- Observed count
- 2
- Probability
- 0.2240418077
Scope and assumptions
Extremely small probabilities may underflow to zero.
NIST statistical methods handbook