Zigeom {VGAM} | R Documentation |
Density, and random generation
for the zero-inflated geometric distribution with parameter pszero
.
dzigeom(x, prob, pszero = 0, log = FALSE) pzigeom(q, prob, pszero = 0) qzigeom(p, prob, pszero = 0) rzigeom(n, prob, pszero = 0)
x, q |
vector of quantiles. |
p |
vector of probabilities. |
prob |
see |
n |
number of observations. |
pszero |
Probability of structural zero (ignoring the geometric distribution), called phi. The default value corresponds to the response having an ordinary geometric distribution. |
log |
Logical. Return the logarithm of the answer? |
The probability function of Y is 0 with probability phi, and geometric(prob) with probability 1-phi. Thus
P(Y=0) = phi + (1-phi) * P(W=0)
where W is distributed geometric(prob).
dzigeom
gives the density,
pzigeom
gives the distribution function,
qzigeom
gives the quantile function, and
rzigeom
generates random deviates.
The argument pszero
is recycled to the required length, and
must have values which lie in the interval [0,1].
Thomas W. Yee
prob = 0.5; pszero = 0.2; x = (-1):20 (ii = dzigeom(x, prob, pszero)) max(abs(cumsum(ii) - pzigeom(x, prob, pszero))) # Should be 0 table(rzigeom(1000, prob, pszero)) ## Not run: x = 0:10 barplot(rbind(dzigeom(x, prob, pszero), dgeom(x, prob)), beside = TRUE, col = c("blue","orange"), ylab = "P[Y = y]", xlab = "y", las = 1, main = paste("zigeometric(", prob, ", pszero = ", pszero, ") (blue) vs", " geometric(", prob, ") (orange)", sep = ""), names.arg = as.character(x)) ## End(Not run)