Get frozen instance of distribution based on predicted parameters.
The parameters of the model.
Explanatory variables for the main count model. If
exogis None, then the data from the model will be used.
Offset is added to the linear predictor of the mean function with coefficient equal to 1. Default is zero if exog is not None, and the model offset if exog is None.
Log(exposure) is added to the linear predictor of the mean function with coefficient equal to 1. If exposure is specified, then it will be logged by the method. The user does not need to log it first. Default is one if exog is is not None, and it is the model exposure if exog is None.