blindrecalc: simulation – R documentation

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simulation

Simulate Rejection Probability and Sample Size for Student's t-Test

Description

This function simulates the probability that a test defined by setupStudent rejects the null hypothesis. Note that here the nuisance parameter nuisance is the variance of the outcome variable sigma^2.

Usage

simulation(
  design,
  n1,
  nuisance,
  recalculation = TRUE,
  delta_true,
  iters = 1000,
  seed = NULL,
  allocation = c("approximate", "exact"),
  ...
)

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 recalcuated after n1 patients are recruited?
`delta_true`	effect measure under which the rejection probabilities are computed
`iters`	Number of simulation iterations.
`seed`	Random seed for simulation.
`allocation`	Whether the allocation ratio should be preserved exactly (`exact`) or approximately (`approximate`).
`...`	Further optional arguments.

Details

The implementation follows the algorithm in Lu (2019): Distribution of the two-sample t-test statistic following blinded sample size re-estimation. Pharmaceutical Statistics 15: 208-215. Since Lu (2019) assumes negative non-inferiority margins, the non-inferiority margin of design is multiplied with -1 internally.

Value

Simulated rejection probabilities and sample sizes for each nuisance parameter.

Examples

d <- setupStudent(alpha = .025, beta = .2, r = 1, delta = 3.5, delta_NI = 0,
                  alternative = "greater", n_max = 156)
simulation(d, n1 = 20, nuisance = 5.5, recalculation = TRUE, delta_true = 3.5)

blindrecalc

Blinded Sample Size Recalculation

v0.1.2

MIT + file LICENSE

Authors

Lukas Baumann [aut], Maximilian Pilz [aut, cre], Institute of Medical Biometry and Informatics - University of Heidelberg [cph]

Initial release