WRSEestimate: Function for calculating WRSE estimates
Description
The function computes the weighted risk set estimates (WRSE) of the survival functions and their estimated standard errors for dynamic treatment regimes (DTRs) at observed event times as proposed in Guo and Tsiatis (2005) Equation (3) and Equation (16).
Usage
WRSEestimate(data)
Arguments
data
a data frame (X, TR, R, Z, U, delta) representing the data from a two-stage randomized designs with therapies A1 and A2 available at the first stage, and B1 and B2 available at the second stage.
X: treatment arm, X=0 for A1, and X=1 for A2
TR: the time t
Value
The function returns an object of class DTR. See DTR.object for details.
Details
In sequentially randomized designs, there could be more than two therapies available at each stage. For simplicity, and to maintain similarity to the most common sequentially randomized clinical trials, a simple two-stage randomization design allowing two treatment options at each stage is used in the current version of the package. In detail, patients are initially randomized to either A1 or A2 at the first stage. Based on their response status, they are then randomized to either B1 or B2 at the second stage. Therefore, there are a total of four DTRs: A1B1, A1B2, A2B1, and A2B2.
References
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