JM (version 0.8-1)

wald.strata: Wald Test for Stratification Factors

Description

It performs a Wald test to test the hypothesis of equal spline coefficients among strata in the approximation of baseline risk function.

Usage

wald.strata(fit)

Arguments

fit

an object of class jointModel with method = "spline-PH-GH" and with a strata specification in the survival part.

Value

• an object of class wald.strata with components:
• alternative
  a character string naming the alternative.
• Result
  a numeric matrix with the results of the Wald test.

Examples

fitLME <- lme(log(serBilir) ~ drug * year - drug, random = ~ year | id, 
    data = pbc2)
fitSURV <- coxph(Surv(years, status2) ~ drug + strata(hepatomegaly), 
    data = pbc2.id, x = TRUE)
fit.pbc <- jointModel(fitLME, fitSURV, timeVar = "year", method = "spline-PH-GH")
wald.strata(fit.pbc)