VGAMdata (version 1.1-12)

otzeta: One-truncated Zeta Distribution Family Function

Description

Estimates the parameter of the 1-truncated zeta distribution.

Usage

otzeta(lshape = "loglink", ishape = NULL,
       gshape = exp((-4:3)/4), zero = NULL)

Value

An object of class "vglmff"

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

Arguments

lshape, ishape, gshape, zero

Same as zetaff. See CommonVGAMffArguments for information.

Author

T. W. Yee

Details

The 1-truncated zeta distribution is the ordinary zeta distribution but with the probability of one being 0. Thus the other probabilities are scaled up (i.e., divided by \(1-P[Y=1]\)). The mean is returned by default as the fitted values. More details can be found at zetaff. Multiple responses are handled.

See Also

Otzeta, zetaff, oizeta, diffzeta, zeta, dzeta, hzeta, zipf.

Examples

if (FALSE) odata <- data.frame(x2 = runif(nn <- 1000))  # Artificial data
odata <- transform(odata, shape = loglink(-0.25 + x2, inverse = TRUE))
odata <- transform(odata, y1 = rotzeta(nn, shape))
with(odata, table(y1))
ofit <- vglm(y1 ~ x2, otzeta, data = odata, trace = TRUE, crit = "coef")
coef(ofit, matrix = TRUE)