VGAM (version 1.1-3)

oilog: One-inflated Logarithmic Distribution Family Function

Description

Fits a 1-inflated logarithmic distribution.

Usage

oilog(lpstr1 = "logitlink", lshape = "logitlink",
      type.fitted = c("mean", "shape", "pobs1", "pstr1", "onempstr1"),
      ishape = NULL, gpstr1 = ppoints(8), gshape = ppoints(8), zero = NULL)

Arguments

lpstr1, lshape

Link functions. For lpstr1: the same idea as zipoisson except it applies to a structural 1.

gpstr1, gshape, ishape

For initial values. See CommonVGAMffArguments for information.

type.fitted, zero

See CommonVGAMffArguments for information.

Value

An object of class "vglmff" (see vglmff-class). The object is used by modelling functions such as vglm, rrvglm and vgam.

Details

The 1-inflated logarithmic distribution is a mixture distribution of the logarithmic distribution with some probability of obtaining a (structural) 1. Thus there are two sources for obtaining the value 1. This distribution is written here in a way that retains a similar notation to the one-inflated positive-Poisson, i.e., the probability \(P[Y=1]\) involves another parameter \(\phi\). See oipospoisson.

This family function can handle multiple responses.

See Also

Gaitlog, Oilog, logff, Oizeta.

Examples

# NOT RUN {
 odata <- data.frame(x2 = runif(nn <- 1000))  # Artificial data
odata <- transform(odata, pstr1 = logitlink(-1 + x2, inverse = TRUE), shape = 0.5)
odata <- transform(odata, y1 = roilog(nn, shape, pstr1 = pstr1))
with(odata, table(y1))
fit1 <- vglm(y1 ~ x2, oilog(zero = "shape"), data = odata, trace = TRUE)
coef(fit1, matrix = TRUE)
# }