contrast_chr {DTR} R Documentation

## Function to compare dynamic treatment regimes (DTRs) based on cumulative hazard ratios (CHRs)

### Description

This function compares the cumulative hazard functions of dynamic treatment regimes (DTRs) from sequentially randomized clinical trials by calculating the natural logarithms of cumulative hazard ratios (CHRs) and performing the Wald-type tests based on natural logarithms of CHRs as proposed in Tang and Wahed (2013) [Epub ahead of print].

### Usage

contrast_chr(est, t = quantile(est\$time, 0.75))


### Arguments

 est the result of a call to the CHRestimate function t a time point of interest. For example, t=5 for the comparisons of survival estimates at 5 years among DTRs. Default t is set to be the 75th percentile of the observed time (i.e. 75th percentile of U).

### Details

Two different comparisons are performed:
1) An overall comparison H0: A1B1=A1B2=A2B1=A2B2
2) Pairwise comparisons including H0: A1B1=A1B2, H0: A1B1=A2B1, H0: A1B1=A2B2, H0: A1B2=A2B1, H0: A1B2=A2B2, and H0: A2B1=A2B2

### Value

The function returns a data frame with four columns: H0, test statistic, df, and p.

 H0 the null hypotheses being tested, for example, H0 (t=3) if the comparisons are made at t=3 test statistic the calculated chi-square test statistic df the degree of freedom p the resulting p-value

### References

Tang X, Wahed AS: Cumulative hazard ratio estimation for treatment regimes in sequentially randomized clinical trials. Statistics in Biosciences, 2013 [Epub ahead of print]

CHRestimate, CHR.object
## Not run: