simplex {VGAM}R Documentation

Simplex distribution

Description

The two parameters of the univariate simplex distribution are estimated.

Usage

simplex(lmu = "logit", lsigma = "loge", 
        emu=list(), esigma=list(),
        imu = NULL, isigma = NULL)

Arguments

lmu Link function for mu. See Links for more choices. The parameter lies in the unit interval.
lsigma Link function for sigma. See Links for more choices. The parameter is positive, therefore the log link is the default.
emu, esigma List. Extra argument for each of the links. See earg in Links for general information.
imu, isigma Optional initial values for mu and sigma. A NULL means a value is obtained internally.

Details

See Jorgensen (1997) for details.

Value

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

Note

This distribution is potentially useful for dispersion modelling. This family function only works for intercept-only models, i.e., the formula should have ~ 1.

Author(s)

T. W. Yee

References

Jorgensen, B. (1997) The Theory of Dispersion Models. London: Chapman & Hall

See Also

rig.

Examples

x = runif(n <- 100)
y = rbeta(n, shape1=3+x, shape2=4-x)
(fit = vglm(y ~ 1, simplex, trace=TRUE, cri="coef"))
coef(fit, matrix=TRUE)
Coef(fit)
summary(fit)

[Package VGAM version 0.7-7 Index]