samplesizeRiskDiffExact: Sample Size for Exact Unconditional Test of Risk Difference

In lrstat: Power and Sample Size Calculation for Non-Proportional Hazards and Beyond

Sample Size for Exact Unconditional Test of Risk Difference

Description

Obtains the sample size given power for exact unconditional test of risk difference.

Usage

samplesizeRiskDiffExact(
  beta = NA_real_,
  riskDiffH0 = 0,
  pi1 = NA_real_,
  pi2 = NA_real_,
  allocationRatioPlanned = 1,
  alpha = 0.025,
  calculateAttainedAlpha = TRUE,
  max_n_search = 1000L,
  window = 10L
)

Arguments

beta	The type II error.
riskDiffH0	The risk difference under the null hypothesis. Defaults to 0.
pi1	The assumed probability for the active treatment group.
pi2	The assumed probability for the control group.
allocationRatioPlanned	Allocation ratio for the active treatment versus control. Defaults to 1 for equal randomization.
alpha	The one-sided significance level.
calculateAttainedAlpha	Whether to calculate the attained alpha.
max_n_search	The maximum sample size to search up to. If no sample size up to this value satisfies the windowed power criterion, an error is thrown.
window	The number of consecutive sample sizes that must all satisfy the power criterion to confirm the found sample size. This is to mitigate non-monotonicity of power in sample size for the exact test.

Value

A data frame with the following variables:

• alpha: The specified one-sided significance level.

• attainedAlpha: The attained one-sided significance level.

• power: The power.

• n: The sample size.

• riskDiffH0: The risk difference under the null hypothesis.

• pi1: The assumed probability for the active treatment group.

• pi2: The assumed probability for the control group.

• allocationRatioPlanned: Allocation ratio for the active treatment versus control.

• zstatRiskDiffBound: The critical value on the scale of score test statistic for risk difference.

• pi2star: The response probability in the control group at which the critical value of the test statistic is attained.

Author(s)

Kaifeng Lu, [e-mail]

Examples

samplesizeRiskDiffExact(beta = 0.2, riskDiffH0 = -0.3,
                        pi1 = 0.8, pi2 = 0.8, alpha = 0.025)

lrstat documentation built on May 13, 2026, 9:06 a.m.