The Beta-binomial Distribution

Source: R/distributions.R

Cumulative density & mass functions, and random number generation for the Beta-binomial distribution using the following re-parameterisation of the Stan Beta-binomial definition:

  • mu = alpha * beta mean probability of trial success.

  • phi = (1 - mu) * beta precision or over-dispersion, component.

dbeta_binomial(x, size, mu, phi, log = FALSE)

pbeta_binomial(q, size, mu, phi, lower.tail = TRUE, log.p = FALSE)

rbeta_binomial(n, size, mu, phi)

Arguments

x, q

Vector of quantiles.

size

Vector of number of trials (zero or more).

mu

Vector of means.

phi

Vector of precisions.

log

Logical; If TRUE, values are returned on the log scale.

lower.tail

Logical; If TRUE (default), return P(X <= x). Else, return P(X > x) .

log.p

Logical; If TRUE, values are returned on the log scale.

n

Number of draws to sample from the distribution.