anova: Anova method for fitted nested models

In seonghobae/flirt.x32: Flexible Item Response Theory Modeling

Description

A generic function to conduct a likelihood ratio test between two nested models.

Usage

## S3 method for class 'flirt'
anova(object, object2, ...)

Arguments

object	an object inheriting from class flirt for the model under the null hypothesis.
object2	an object inheriting from class flirt for the model under the alternative hypothesis.
...	additional arguments; currently none is used.

Value

An object of either class anova.flirt with components,

name0	the name of object.
L0	the log-likelihood under the null hypothesis (object).
aic0	the AIC value for the model given by object.
bic0	the BIC value for the model given by object.
name1	the name of object2.
L1	the log-likelihood under the alternative hypothesis (object2).
aic1	the AIC value for the model given by object2.
bic1	the BIC value for the model given by object2.
LRT	the value of the Likelihood Ratio Test statistic.
df	the degrees of freedom for the test (i.e., the difference in the number of parameters).
p.value	the p-value of the test.

Warning

The code does not check if the models are nested. The user is responsible to supply nested models in order for the LRT to be valid.

Author(s)

Minjeong Jeon <[e-mail]>

See Also

flirt, logLik

Examples

library(flirt)

## verbal aggression data

data(verb2)

# 2-dimensional 2PL model for binary data: a(th+b) parameterization
model1 <- flirt(data=verb2, select=2:25, loading=list(on=TRUE, inside=TRUE),  
            mul=list(on=TRUE, dim_info=list(dim1=1:12, dim2=13:24))  )

#  2-dimensional Rasch model 
model2 <- flirt(data=verb2, select=2:25, 
            mul=list(on=TRUE, dim_info=list(dim1=1:12, dim2=13:24))  )

# LR test
anova(model2, model1) # model1 is nested within model2

seonghobae/flirt.x32 documentation built on May 29, 2019, 6:54 p.m.