blindrecalc (version 1.1.0)

adjusted_alpha,Student-method: Adjusted level of significance

Description

This method returns an adjusted significance level that can be used such that the actual type I error rate is preserved.

Usage

# S4 method for Student
adjusted_alpha(
  design,
  n1,
  nuisance,
  recalculation,
  tol,
  iters = 10000,
  seed = NULL,
  ...
)

Value

Value of the adjusted significance level for every nuisance parameter and every value of n1.

Arguments

design

Object of class Student created by setupStudent.

n1

Either the sample size of the first stage (if recalculation = TRUE or the toal sample size (if recalculation = FALSE).

nuisance

Value of the nuisance parameter. For the Student's t-test this is the variance.

recalculation

Should the sample size be recalculated after n1 patients are recruited?

tol

desired absolute tolerance

iters

Number of simulation iterations.

seed

Random seed for simulation.

...

Further optional arguments.

Details

The method is only vectorized in either nuisance or n1.

In the case of the Student's t-test, the adjusted alpha is calculated using the algorithm by Kieser and Friede (2000): "Re-calculating the sample size in internal pilot study designs with control of the type I error rate". Statistics in Medicine 19: 901-911.

Examples

d <- setupStudent(alpha = .025, beta = .2, r = 1, delta = 0, delta_NI = 1.5,
                  n_max = 848)
sigma <- c(2, 5.5, 9)
adjusted_alpha(design = d, n1 = 20, nuisance = sigma, recalculation = TRUE,
               tol = 1e-4, iters = 1e3)