lrtest: Likelihood Ratio Test

In rld: Analyze and Design Repeated Low-Dose Challenge Experiments

Description

This function performs likelihood ratio test (LRT) to test regression paramters in the mean model and frailty variance paramter nu.

Usage

lrtest(model1, model2, TestNu=TRUE, Siglevel=0.05)

Arguments

model1	a result of the nested model which is returned by rld.
model2	a result of the full model which is returned by rld.
TestNu	logic value: If TRUE, the frailty variance paramter will be tested. Otherwise, the regression parameters will be tested. The default is TRUE.
Siglevel	a value: significance level. The default is 0.05.

Details

Under the null hypothesis of frailty variance parameter nu=0, the test statistic converges to a mixture of chi-squared distribution. For regression parameters, under the null hypothesis beta=0, the test statistic converges to chi-squared distribution. Please refer to Kang et al.(2015) for more details.

Value

statistic	a value: test statistic.
df	a value: degree of freedom.
pvalue	the p-value.

Author(s)

Bin Yao, Ying Huang and Chaeryon Kang

References

Kang, C., Huang, Y., and Miller, C. (2015). A discrete-time survival model with random effects for designing and analyzing repeated low-dose challenge experiments. Biostatistics, 16(2): 295-310.

See Also

rld

Examples

#test frailty variance parameter
data(SampleData)
newdata <- transdata(data = SampleData, ndlevel = 3, nexposure = c(10, 10, 2))
fitout1 <- rld(formula = survival::Surv(time, delta)~factor(trt)+factor(dose), data = newdata,
               frailty = FALSE)
fitout2 <- rld(formula = survival::Surv(time, delta)~factor(trt)+factor(dose), data = newdata,
               frailty = TRUE)
testnu <- lrtest(model1 = fitout1, model2 = fitout2, TestNu=TRUE)

## Not run: 
#test regression parameters
fitout3 <- rld(formula = survival::Surv(time, delta)~factor(dose), data = newdata,
               frailty = TRUE)
fitout4 <- rld(formula = survival::Surv(time, delta)~factor(trt)+factor(dose), data = newdata,
               frailty = TRUE)
testbeta <- lrtest(model1 = fitout3, model2 = fitout4, TestNu=FALSE)

## End(Not run)

Example output

rld documentation built on May 2, 2019, 5:57 a.m.