anova {JM}R Documentation

Anova Method for Fitted Joint Models

Description

Performs a likelihood ratio test between two nested joint models.

Usage

## S3 method for class 'jointModel':
anova(object, object2, test = TRUE, ...)

Arguments

object an object inheriting from class jointModel, nested in object2.
object2 an object inheriting from class jointModel.
test logical; if TRUE the likelihood ratio test is performed.
... additional arguments; currently none is used.

Value

An object of class aov.jointModel with components,

nam0 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.
nam1 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.
df the degrees of freedom for the test (i.e., the difference in the number of parameters).
LRT the value of the Likelihood Ratio Test statistic (returned if test = TRUE).
p.value the p-value of the test (returned if test = TRUE).

Warning

The code minimally checks whether the models are nested! The user is responsible to supply nested models in order the LRT to be valid.

Author(s)

Dimitris Rizopoulos d.rizopoulos@erasmusmc.nl

See Also

jointModel

Examples

# linear mixed model fit without treatment effect
fitLME.null <- lme(sqrt(CD4) ~ obstime, 
    random = ~ 1 | patient, data = aids)
# cox model fit without treatment effect
fitCOX.null <- coxph(Surv(Time, death) ~ 1, 
    data = aids.id, x = TRUE)
# joint model fit, under the additive log cumulative hazard model 
# without treatment effect
fitJOINT.null <- jointModel(fitLME.null, fitCOX.null, 
    timeVar = "obstime", method = "ch-GH")

# linear mixed model fit with treatment effect
fitLME.alt <- lme(sqrt(CD4) ~ obstime * drug - drug, 
    random = ~ 1 | patient, data = aids)
# cox model fit with treatment effect
fitCOX.alt <- coxph(Surv(Time, death) ~ drug, 
    data = aids.id, x = TRUE)
# joint model fit, under the additive log cumulative hazard model 
# with treatment effect
fitJOINT.alt <- jointModel(fitLME.alt, fitCOX.alt, timeVar = "obstime", 
    method = "ch-GH")

# likelihood ratio test for treatment effect
anova(fitJOINT.null, fitJOINT.alt)

[Package JM version 0.2-2 Index]