glm.convert {MASS} | R Documentation

## Change a Negative Binomial fit to a GLM fit

### Description

This function modifies an output object from `glm.nb()` to one that looks like the output from `glm()` with a negative binomial family. This allows it to be updated keeping the theta parameter fixed.

### Usage

    glm.convert(object)

### Arguments

`object` | An object of class `"negbin"`, typically the output from `glm.nb()`.

### Details

Convenience function needed to effect some low level changes to the structure of the fitted model object.

### Value

An object of class `"glm"` with negative binomial family. The theta parameter is then fixed at its present estimate.

### See Also

`glm.nb`, `negative.binomial`, `glm`

### Examples

    quine.nb1 <- glm.nb(Days ~ Sex/(Age + Eth*Lrn), data = quine)
    quine.nbA <- glm.convert(quine.nb1)
    quine.nbB <- update(quine.nb1, . ~ . + Sex:Age:Lrn)
    anova(quine.nbA, quine.nbB)

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