P ProbLab
Tools/Poisson Event Estimator

Poisson Event Estimator

Compute probabilities for Poisson events: customer arrivals per hour, server incidents per day, rare diseases per year. Includes a staffing recommendation that picks a capacity with low probability of overload.

Setup

Advertisement

Result

Distribution (k = 0 to λ+3σ)

When to use Poisson

Use Poisson when events occur independently, at a known average rate, in a continuous interval. Good fits: call-center arrivals, traffic accidents per mile, radioactive decays, rare diseases per population. Bad fits: anything where events cluster (rush-hour traffic) — use a non-homogeneous Poisson process instead.

Who uses it

  • Operations managers sizing call-center staffing.
  • SREs modeling incident rates and alert thresholds.
  • Epidemiologists analyzing rare-disease incidence.

Limitations

  • Independent-events assumption is violated for clustered events (rush hour, contagious disease).
  • Mean equals variance in Poisson. If your data has over-dispersion (variance > mean), use negative binomial instead.