Zinegbin {VGAM} | R Documentation |
Density, distribution function, quantile function and random generation
for the zero-inflated negative binomial distribution with parameter phi
.
dzinegbin(x, phi, size, prob = NULL, munb = NULL, log = FALSE) pzinegbin(q, phi, size, prob = NULL, munb = NULL) qzinegbin(p, phi, size, prob = NULL, munb = NULL) rzinegbin(n, phi, size, prob = NULL, munb = NULL)
x, q |
vector of quantiles. |
p |
vector of probabilities. |
n |
number of observations. Must be a single positive integer. |
size, prob, munb, log |
Arguments matching |
phi |
Probability of zero (ignoring the negative binomial distribution), called phi. |
The probability function of Y is 0 with probability phi, and a negative binomial distribution with probability 1-phi. Thus
P(Y=0) = phi + (1-phi) * P(W=0)
where W is distributed as a negative binomial distribution
(see rnbinom
.)
See negbinomial
, a VGAM family function,
for the formula of the probability density function and other details
of the negative binomial distribution.
dzinegbin
gives the density,
pzinegbin
gives the distribution function,
qzinegbin
gives the quantile function, and
rzinegbin
generates random deviates.
The argument phi
is recycled to the required length, and
must have values which lie in the interval [0,1].
Thomas W. Yee
zinegbinomial
,
rnbinom
,
rzipois
.
munb = 3; phi = 0.2; size = k = 10 x = 0:10 (ii = dzinegbin(x, phi = phi, mu = munb, size = k)) max(abs(cumsum(ii) - pzinegbin(x, phi = phi, mu = munb, size = k))) # Should be 0 table(rzinegbin(100, phi = phi, mu = munb, size = k)) table(qzinegbin(runif(1000), phi = phi, mu = munb, size = k)) round(dzinegbin(x, phi = phi, mu = munb, size = k) * 1000) # Should be similar ## Not run: barplot(rbind(dzinegbin(x, phi = phi, mu = munb, size = k), dnbinom(x, mu = munb, size = k)), beside = TRUE, col = c("blue", "green"), main = paste("ZINB(mu = ", munb, ", k = ", k, ", phi = ", phi, ") (blue) vs negative binomial(mu = ", munb, ", size = ", k, ") (green)", sep = ""), names.arg = as.character(x)) ## End(Not run)