R: Zero-inflated negative binomial distribution

dzinbinom {emdbook} | R Documentation

## Zero-inflated negative binomial distribution

### Description

Probability distribution function and random variate generation for the zero-inflated negative binomial distribution

### Usage

    dzinbinom(x, mu, size, zprob, log=FALSE)
    rzinbinom(n, mu, size, zprob)

### Arguments

`x` | vector of integer values
`n` | number of values to draw
`mu` | mean parameter (or vector of parameters) of negative binomial
`size` | number of trials/overdispersion parameter (or vector of parameters) of negative binomial
`zprob` | probability of structural zeros
`log` | return log probability?

### Details

The zero-inflated negative binomial distribution is widely used to model extra zero counts in count data that otherwise follows a negative binomial distribution. The probability distribution is

p(0) = pz + (1-pz) NB(0,mu,k)

and

p(x) = (1-pz) NB(x,mu,k)

for x>0.

### Value

Probabilities of x or random deviates.

### Note

Only the "ecological" parameterization is included here (must specify `mu`, not `prob`)

### Author(s)

Ben Bolker

### References

Tyre et al., "Improving precision and reducing bias in biological surveys: estimating false-negative error rates", Ecological Applications 13:1790-1801 (2003)

### See Also

`dnbinom`, Simon Jackman's pscl package

### Examples

    dzinbinom(0:9,mu=2,zprob=0.3,size=0.9)
    dnbinom(0:9,mu=2,size=0.9)
    rzinbinom(10,mu=2,zprob=0.3,size=0.9)

[Package emdbook version 1.3.9 Index]