statsmodels.discrete.discrete_model.Poisson.pdf

Poisson.pdf(X) [source]

Poisson model probability mass function

Parameters:	X (array-like) – X is the linear predictor of the model. See notes.
Returns:	pdf – The value of the Poisson probability mass function, PMF, for each point of X.
Return type:	ndarray

Notes

The PMF is defined as

\[\frac{e^{-\lambda_{i}}\lambda_{i}^{y_{i}}}{y_{i}!}\]

where \(\lambda\) assumes the loglinear model. I.e.,

\[\ln\lambda_{i}=x_{i}\beta\]

The parameter X is \(x_{i}\beta\) in the above formula.