anova.gnm {glmtoolbox}

Comparison of nested models in Generalized Nonlinear Models.

Description

Allows to use the likelihood-ratio test to compare nested models in generalized nonlinear models.

Usage

## S3 method for class 'gnm'
anova(object, ..., verbose = TRUE)

Arguments

object

an object of the class gnm.

...

another objects of the class gnm.

verbose

an (optional) logical indicating if should the report of results be printed. As default, verbose is set to TRUE.

Value

A matrix with the following three columns:

Chi	The value of the statistic of the test,
Df	The number of degrees of freedom,
Pr(>Chi)	The p-value of the test-type test computed using the Chi-square distribution.

Examples

###### Example: The effects of fertilizers on coastal Bermuda grass
data(Grass)
fit1 <- gnm(Yield ~ b0 + b1/(Nitrogen + a1) + b2/(Phosphorus + a2) + b3/(Potassium + a3),
            family=gaussian(inverse), start=c(b0=0.1,b1=13,b2=1,b3=1,a1=45,a2=15,a3=30), data=Grass)

fit2 <- update(fit1,Yield ~ I(b0 + b2/(Phosphorus + a2) + b3/(Potassium + a3)),
               start=c(b0=0.1,b2=1,b3=1,a2=15,a3=30))

anova(fit2,fit1)