dzibinom: Zero-inflated binomial probability density

In rmcelreath/rethinking: Statistical Rethinking book package

Zero-inflated binomial probability density

Description

Functions for computing density and producing random samples from a zero-inflated binomial probability distribution.

Usage

dzibinom( x , p_zero , size , prob , log=FALSE )
rzibinom( n , p_zero , size , prob )

Arguments

x	Integer values to compute densities or probabilies of
p_zero	Probability of a zero from bernoulli process
size	Number of binomial trials
prob	Probability of success in binomial trial
log	If TRUE, returns log-probability instead of probability

Details

These functions provide density and random number calculations for zero-inflated binomial observations. This distribution is defined as a finite mixture of zeros and binomial values, where p_zero determines the weight of the pure zeros. As such, the probability of a zero is p_zero + (1-p_zero)(1-prob)^size. And the probability of a non-zero value x is (1-p_zero) choose(size,x) prob^x (1-prob)^(size-x).

dzibinom does its calculations in a way meant to reduce numerical issues with probabilities close to 0 and 1. As a result, it's not very fast.

Author(s)

Richard McElreath

rmcelreath/rethinking documentation built on Aug. 26, 2024, 5:54 p.m.