gs_b: Default boundary generation

In gsDesign2: Group Sequential Design with Non-Constant Effect

Default boundary generation

Description

gs_b() is the simplest version of a function to be used with the upper and lower arguments in gs_power_npe() and gs_design_npe() or the upper_bound and lower_bound arguments in gs_prob_combo() and pmvnorm_combo(). It simply returns the vector of Z-values in the input vector par or, if k is specified, par[k] is returned. Note that if bounds need to change with changing information at analyses, gs_b() should not be used. For instance, for spending function bounds use gs_spending_bound().

Usage

gs_b(par = NULL, k = NULL, ...)

Arguments

par	For gs_b(), this is just Z-values for the boundaries; can include infinite values.
k	Is NULL (default), return par, else return par[k].
...	Further arguments passed to or from other methods.

Value

Returns the vector input par if k is NULL, otherwise, par[k].

Specification

The contents of this section are shown in PDF user manual only.

Examples

# Simple: enter a vector of length 3 for bound
gs_b(par = 4:2)

# 2nd element of par
gs_b(par = 4:2, k = 2)

# Generate an efficacy bound using a spending function
# Use Lan-DeMets spending approximation of O'Brien-Fleming bound
# as 50%, 75% and 100% of final spending
# Information fraction
IF <- c(.5, .75, 1)
gs_b(par = gsDesign::gsDesign(
  alpha = .025, k = length(IF),
  test.type = 1, sfu = gsDesign::sfLDOF,
  timing = IF
)$upper$bound)

gsDesign2 documentation built on April 3, 2025, 9:39 p.m.