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

 `1` ```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.

`rld`

Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18``` ```#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.