Description Usage Arguments Details Value References See Also Examples

This function compares the survival estimates at specific time point among dynamic treatment regimes (DTRs) using the Wald-type tests.

1 | ```
contrast_wald(est, t = quantile(est$time, 0.75))
``` |

`est` |
the result of a call to the |

`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). |

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

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 |

Lunceford JK, Davidian M, Tsiatis AA: Estimation of survival distributions of treatment policies in two-stage randomization designs in clinical trials. Biometrics 58:48-57, 2002

Guo X, Tsiatis AA: A weighted risk set estimator for survival distributions in two-stage randomization designs with censored survival data. Int. J. Biostatistics 1:1-15, 2005

`LDTestimate`

, `WRSEestimate`

, `DTR.object`

1 2 3 4 5 6 7 8 9 10 11 12 | ```
## Not run:
# LDT estimates
data("LDTdata")
est <- LDTestimate(data=LDTdata)
contrast_wald(est, t=1)
# WRSE estimates
data("WRSEdata")
est <- WRSEestimate(data=WRSEdata)
contrast_wald(est, t=300)
## End(Not run)
``` |

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