Functions for computing density and producing random samples from a zero-inflated binomial probability distribution.
dzibinom( x , p_zero , size , prob , log=FALSE )
rzibinom( n , p_zero , size , prob )Integer values to compute densities or probabilies of
Probability of a zero from bernoulli process
Number of binomial trials
Probability of success in binomial trial
If TRUE, returns log-probability instead of probability
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.