Zero-inflated Poisson distribution
= Zero-inflated Poisson distribution
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A zero-inflated <Poisson distribution> is a mixture of a point mass at zero and a <Poisson distribution>. If the Poisson component has weight $\pi$ and <mean> $\lambda$, then its <mean> is $\pi\lambda$ and its <variance> is $\pi\lambda+\pi(1-\pi)\lambda^2$.