powerNicqTest: Power or Sample Size for Non-inferiority Control Quantile Test

Description

Function gives power (if n1=NULL) or sample size (if power=NULL). Assumes no ties.

Usage

powerNicqTest(n1 = NULL, n2 = NULL, power = NULL, 
    sig.level = 0.025, n2.over.n1 = 1, q = 0.2, 
    delta0 = 0.1, alternative = c("less", "greater"), 
    gnull = nimDiffOR, galt = function(x){x}, 
    minn=5, maxn = 10^5, ...)

Value

a power.htest object. A list with elements:

n1: sample size for control group
n2: sample size for test group
delta0: F2(tau)-F1(tau), with tau defined by F1(tau)=q
q: probability associated with tau
sig.level: significance level
power: power under galt
method: character description of method

Arguments

n1: sample size of control group, calculated if NULL
n2: sample size of test group. If n1=NULL, n2 is ignored and calculated based on power and n2.over.n1. If power=NULL, then n2=ceiling(n2.over.n1*n1).
power: power under galt, calculated if NULL
sig.level: significance level
n2.over.n1: ratio of sample sizes
q: probability associated with control quantile of interest
delta0: difference in proportions at control quantile of interest
alternative: alternative hypothesis direction, 'less' means F2(t) less than gnull(F1(t)) for some t.
gnull: variable margin function under null hypothesis (more formally, at the boundary between the null and alternative hypotheses for the pre-specified hypotheses)
galt: variable margin function for which we calculate the power
minn: minimum value for sample size for n1, input into uniroot.integer.
maxn: maximum value for sample size for n1, input into uniroot.integer.
...: extra arguments passed to uniroot.integer.

Details

The function either calculates the power (if n1=NULL) or calculates n1 and n2 (if power=NULL). In the latter case, we use uniroot.integer to find the smallest n1 that gives power at least as large as the given power [with n2 defined as ceiling(n2.over.n1*n1)].

Examples

Run this code

# to calculate power, leave power=NULL and supply n1 and n2
powerNicqTest(n1=200,n2=300)
# or supply n1 and n2.over.n1
powerNicqTest(n1=200,n2.over.n1=3/2)
## to calculate n1 and n2, supply power
## find minimum n1 that have power greater than 0.80
## takes 13 iterations to find n1=346
## so do not run it here
#powerNicqTest(power=.80,print.steps=TRUE)