findconst.surv {stoppingrule}

Search for Calibration Value (Survival Data)

Description

Internal workhorse function to calculate the calibration constant value that attains level alpha for given method for time-to-event data

Usage

findconst.surv(n, p0, alpha, type, tau, param = NULL)

Arguments

n

Maximum sample size for safety monitoring

p0

The probability of a toxicity occurring in tau units of time under the null hypothesis

alpha

The nominal type I error/false positive rate for the stopping rule, under an assumption that the cumulative number of events follows a Poisson process over the study duration.

type

The method used for constructing the stopping rule

tau

Length of observation period

param

A vector of the extra parameter(s) needed for certain stopping rule methods. For Wang-Tsiatis tests, this is the Delta parameter. For truncated SPRT, this is the targeted alternative toxicity probability p1. For Bayesian Gamma-Poisson model, this is the vector of hyperparameters (shape,rate) for the gamma prior on the toxicity event rate.

Value

The calibration constant used for subsequent stopping boundary calculation