N.APPLE {DelayedEffect.Design}

APPLE sample size computation

Description

Perform the sample size calculation given the power and post-delay hazard ratio using the closeform APPLE method based on the piecewise weighted log-rank test when the treatment time-lag effect is present and the lag duration is homogeneous across the individual subject

Usage

 N.APPLE(lambda1, t1, p, HR, tao, A, beta, ap=0.5, alpha=0.05)

Arguments

lambda1

Baseline hazard or NULL (see details)

t1

Delayed duration or NULL (see details)

p

Proportion of subjects who survive beyond the delayed period or NULL (see details)

HR

Post-delay hazard ratio, defined as the post-delay hazard rate of the treatment group compared to that of the control group

tao

Total study duration

A

Total enrollment duration

beta

Type II error rate; Power=1-beta

ap

Experimental-control allocation ratio. The default is 0.5.

alpha

Type I error rate (two-sided). The default is 0.05.

Details

APPLE is an acronym for:
Analytic Power calculation method based on Piecewise weighted Log-rank tEst. See the reference for details of this method.

Out of the three input parameters lambda1, t1 and p, only two need to be specified, the remaining one will be computed internally from the formula lambda1 = -log(p)/t1. If all three are not NULL, then lambda1 will be set to -log(p)/t1 regardless of the user input value.

Value

The sample size

Author(s)

Zhenzhen Xu <[e-mail]>, Boguang Zhen<[e-mail]>, Yongsoek Park <[e-mail]> and Bin Zhu <[e-mail]>

References

Xu, Z., Zhen, B., Park, Y., & Zhu, B. (2017). Designing therapeutic cancer vaccine trials with delayed treatment effect. Statistics in medicine, 36(4), 592-605.

See Also

pow.APPLE, HR.APPLE

Examples

  lambda1 <- NULL
  t1      <- 183
  p       <- 0.7
  HR      <- 0.55
  tao     <- 365*3
  A       <- 365
  beta    <- 0.2
  N.APPLE(lambda1, t1, p, HR, tao, A, beta)