Plans a group sequential trial (GST
)
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K |
number of stages |
t |
vector with the cumulative information fraction (default: (1:K)/K) |
Imax |
maximum information number (default: NULL) |
SF |
spending function (for details see below) |
phi |
parameter of spending function when SF=3 or 4 (See below) |
alpha |
alpha (type I error rate) |
delta |
effect size (alternative)(default: NULL) |
pow |
power (default: NULL) |
compute.alab |
specify if alpha-absorbing parameter values should be calculated (default: TRUE) |
compute.als |
specify if alpha-values ”spent” at every stage should be calculated (default: TRUE) |
The user has to specify either Imax
or delta
and pow
.
If all three items are specified, the pre-defined maximum information number is newly calculated from the information for delta
and power
, and Imax
is overwritten.
SF
defines the spending function.
SF = | 1 O'Brien and Fleming type spending function of Lan and DeMets (1983) |
SF = | 2 Pocock type spending function of Lan and DeMets (1983) |
SF = | 3 Power family (c_α* t^φ); phi must be greater than 0 |
SF = | 4 Hwang-Shih-DeCani family; (1-e^{-φ t})/(1-e^{-φ}), where phi cannot be 0 |
plan.GST
returns an object of the class
GSTobj
.
An object of class GSTobj
is a list containing the following
components:
K |
number of stages |
a |
lower critical bounds of group sequential design (are currently always set to -8) |
b |
upper critical bounds of group sequential design |
t |
vector with cumulative information fraction |
al |
alpha (type I error) |
SF |
spending function |
phi |
parameter of spending function when SF=3 or 4 (See below) |
Imax |
maximum information number |
delta |
effect size used for planning the primary trial |
Niklas Hack niklas.hack@meduniwien.ac.at and Werner Brannath werner.brannath@meduniwien.ac.at
Brannath, W, Mehta, CR, Posch, M (2008) ”Exact confidence bounds following adaptive group sequential tests”, Biometrics accepted.
GSTobj
, print.GSTobj
, plot.GSTobj
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Questions? Problems? Suggestions? Tweet to @rdrrHQ or email at ian@mutexlabs.com.
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