anova.clm: ANODE Tables and Likelihood ratio test of cumulative link models

Description

Type I, II, and III analysis of deviance (ANODE) tables for cumulative link models and comparison of cumulative link models with likelihood ratio tests. Models may differ by terms in location, scale and nominal formulae, in link, threshold function.

Usage

# S3 method for clm
anova(object, ..., type = c("I", "II", "III", "1", "2", "3"))

Arguments

object

a clm object.

…

optionally one or more additional clm objects.

type

the type of hypothesis test if anova is called with a single model; ignored if more than one model is passed to the method.

Value

An analysis of deviance table based on Wald chi-square test if called with a single model and a comparison of models with likelihood ratio tests if called with more than one model.

Details

The ANODE table returned when anova is called with a single model apply only to terms in formula, that is, terms in nominal and scale are ignored.

Examples

Run this code

# NOT RUN {
## Analysis of deviance tables with Wald chi-square tests:
fm <- clm(rating ~ temp * contact, scale=~contact, data=wine)
anova(fm, type="I")
anova(fm, type="II")
anova(fm, type="III")

options(contrasts = c("contr.treatment", "contr.poly"))
m1 <- clm2(SURENESS ~ PROD, scale = ~PROD, data = soup,
          link = "logistic")

## anova
anova(m1, update(m1, scale = ~.-PROD))
mN1 <- clm2(SURENESS ~ 1, nominal = ~PROD, data = soup,
           link = "logistic")
anova(m1, mN1)
anova(m1, update(m1, scale = ~.-PROD), mN1)

## Fit model from polr example:
if(require(MASS)) {
    fm1 <- clm2(Sat ~ Infl + Type + Cont, weights = Freq, data = housing)
    anova(fm1, update(fm1, scale =~ Cont))
}

# }