has.interceptvlm {VGAM} | R Documentation

## Has a Fitted VGLM Got an Intercept Term?

### Description

Looks at the `formula` to see if it has an intercept term.

### Usage

    has.intercept(object, ...)
    has.interceptvlm(object, form.number = 1, ...)

### Arguments

`object` | A fitted model object.
`form.number` | Formula number, is 1 or 2. which correspond to the arguments `formula` and `form2` respectively.
`...` | Arguments that are might be passed from one function to another.

### Details

This methods function is a simple way to determine whether a fitted `vglm` object etc. has an intercept term or not. It is not entirely foolproof because one might suppress the intercept from the formula and then add in a variable in the formula that has a constant value.

### Value

Returns a single logical.

### Author(s)

Thomas W. Yee

### See Also

`formulavlm`, `termsvlm`.

### Examples

    # Example: this is based on a glm example
    counts <- c(18,17,15,20,10,20,25,13,12)
    outcome <- gl(3, 1, 9); treatment <- gl(3, 3)
    pdata <- data.frame(counts, outcome, treatment)  # Better style
    vglm.D93 <- vglm(counts ~ outcome + treatment, poissonff, data = pdata)
    formula(vglm.D93)
    term.names(vglm.D93)
    responseName(vglm.D93)
    has.intercept(vglm.D93)

[Package VGAM version 1.1-1 Index]