pymc.ZeroInflatedPoisson#

class pymc.ZeroInflatedPoisson(name, psi, mu, **kwargs)[source]#

Zero-inflated Poisson log-likelihood.

Often used to model the number of events occurring in a fixed period of time when the times at which events occur are independent. The pmf of this distribution is

$\begin{split}f(x \mid \psi, \mu) = \left\{ \begin{array}{l} (1-\psi) + \psi e^{-\mu}, \text{if } x = 0 \\ \psi \frac{e^{-\theta}\theta^x}{x!}, \text{if } x=1,2,3,\ldots \end{array} \right.\end{split}$
 Support $$x \in \mathbb{N}_0$$ Mean $$\psi\mu$$ Variance $$\mu + \frac{1-\psi}{\psi}\mu^2$$
Parameters
psi

Expected proportion of Poisson variates (0 < psi < 1)

mu

Expected number of occurrences during the given interval (mu >= 0).

Methods

 ZeroInflatedPoisson.__init__(*args, **kwargs) ZeroInflatedPoisson.dist(psi, mu, **kwargs)