glm.convert               package: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)

