Efficacy Boundaries for Group Sequential Design

Obtains the efficacy stopping boundaries for a group sequential design.

Usage

getBound(
  k = NA_integer_,
  informationRates = NA_real_,
  alpha = 0.025,
  typeAlphaSpending = "sfOF",
  parameterAlphaSpending = NA_real_,
  userAlphaSpending = NA_real_,
  spendingTime = NA_real_,
  efficacyStopping = NA_integer_
)

Arguments

k

Look number for the current analysis.

informationRates

Information rates up to the current look. Must be increasing and less than or equal to 1.

alpha

The significance level. Defaults to 0.025.

typeAlphaSpending

The type of alpha spending. One of the following: "OF" for O'Brien-Fleming boundaries, "P" for Pocock boundaries, "WT" for Wang & Tsiatis boundaries, "sfOF" for O'Brien-Fleming type spending function, "sfP" for Pocock type spending function, "sfKD" for Kim & DeMets spending function, "sfHSD" for Hwang, Shi & DeCani spending function, "user" for user defined spending, and "none" for no early efficacy stopping. Defaults to "sfOF".

parameterAlphaSpending

The parameter value for the alpha spending. Corresponds to \(\Delta\) for "WT", \(\rho\) for "sfKD", and \(\gamma\) for "sfHSD".

userAlphaSpending

The user defined alpha spending. Cumulative alpha spent up to each stage.

spendingTime

A vector of length k for the error spending time at each analysis. Must be increasing and less than or equal to 1. Defaults to missing, in which case, it is the same as informationRates.

efficacyStopping

Indicators of whether efficacy stopping is allowed at each stage. Defaults to TRUE if left unspecified.

Value

A numeric vector of critical values up to the current look.

Details

If typeAlphaSpending is "OF", "P", or "WT", then the boundaries will be based on equally spaced looks.

Author

Kaifeng Lu, kaifenglu@gmail.com

Examples

getBound(k = 2, informationRates = c(0.5,1),
         alpha = 0.025, typeAlphaSpending = "sfOF")
#> [1] 2.962588 1.968596