pwr_overall_pois function

Power Calculation from Sample Size

Power Calculation from Sample Size

Calculates the study power to detect a set of effects given a particular sample size in a two-stage randomized clinical trial

pwr_overall_pois( N, phi, lambda11, lambda22, lambda1, lambda2, alpha = 0.05, theta = 0.5, xi = 1, nstrata = 1 )

Arguments

  • N: overall study sample size.
  • phi: the proportion of patients preferring treatment 1. Should be numeric value between 0 and 1. If study is stratified, should be vector with length equal to the number of strata in the study.
  • lambda11: response mean of patients choosing to receive treatment 1 in the choice arm. Should be numeric value larger than 0. If study is stratified, should be vector with length equal to the number of strata in the study.
  • lambda22: response mean of patients choosing to receive treatment 2 in the choice arm. Should be numeric value larger than 0. If study is stratified, should be vector with length equal to the number of strata in the study.
  • lambda1: response mean of patients randomized to receive treatment 1 in the random arm. Should be numeric value larger than 0. If study is stratified, should be vector with length equal to the number of strata in the study.
  • lambda2: response mean of patients randomized to receive treatment 2 in the random arm. Should be numeric value larger than 0. If study is stratified, should be vector with length equal to the number of strata in the study.
  • alpha: desired type I error rate.
  • theta: proportion of patients assigned to choice arm in the initial randomization. Should be numeric value between 0 and 1 (default=0.5).
  • xi: a numeric vector of the proportion of patients in each stratum. Length of vector should equal the number of strata in the study and sum of vector should be 1. All vector elements should be numeric values between 0 and 1. Default is 1 (i.e. unstratified design).
  • nstrata: number of strata. Default is 1 (i.e. unstratified design).

Examples

# Unstratified pwr_overall_pois(N=400, phi=0.5, lambda11=0.8, lambda22=0.5, lambda1=0.5, lambda2=0.4) # Stratified pwr_overall_pois(N=400, phi=c(0.5,0.5), lambda11=c(0.7,0.8), lambda22=c(0.4,0.4), lambda1=c(0.5,0.4), lambda2=c(0.2,0.3), xi=c(0.3,0.7), nstrata=2)