Sim {OneArm2stage}

Calculate Empirical Power by Simulation for Two-Stage Designs Using One-Sample Log-Rank Test

Description

Sim() can be used to calculate the empirical power and type-I error by simulation given the design parameters obtained from the two-stage designs using phase2.TTE().

Usage

Sim(
  shape,
  S0,
  S1,
  x0,
  tf,
  rate,
  t1,
  c1,
  c,
  n1,
  n,
  N,
  restricted = 0,
  seed = 123
)

Arguments

shape

shape parameter of the baseline hazard function assuming Weibull distribution.

S0

survival probability at a fixed time point x0 under the null hypothesis.

S1

survival probability at a fixed time point x0 under the alternative hypothesis.

x0

a fixed time point where the survival probabilities are known for both null and alternative hypotheses.

tf

the follow-up time, the time period from the entry of the last patient to the end of the trial.

rate

a constant accrual rate.

t1

the interim analysis time as given by the two-stage design.

c1

the critical value for the interim analysis as given by the two-stage design.

c

the critical value for the final analysis as given by the two-stage design.

n1

the required sample size for the interim analysis as given by the two-stage design.

n

the required total sample size for the entire trial as given by the two-stage design.

N

number of trials in the simulation.

restricted

if restricted = 0 (default value), unrestricted follow-up is used. If restricted = 1 or any other values, restricted follow-up is used.

seed

seed for random number generation.

Value

a numeric value that is either the empirical power (when S1=S0^hr) or the type I-error (when S1=S0).

Examples

# calculate empirical power and type I error given design parameters
Sim(shape=1, S0=0.62, S1=0.62^(0.467), x0=2, tf=2, rate=5, t1=3.0593,
    c1=-0.302, c=1.6135, n1=16, n=26, N=10000, seed=5868)
# empirical power
# 0.813

Sim(shape=1, S0=0.62, S1=0.62, x0=2, tf=2, rate=5, t1=3.0593,
    c1=-0.302, c=1.6135, n1=16, n=26, N=10000, seed=5868)
# empirical type-I error
# 0.037