alphaByUseFunction {GroupSeq}R Documentation

Computes alpha by a use function

Description

This function computes type I error to spend at each analysis using an alpha-spending function.

Usage

alphaByUseFunction(whatSpendingFunctionIsUsed, n, alpha, phi, OneOrTwoSidedBounds, t)

Arguments

whatSpendingFunctionIsUsed indicates type I error spending rate function and is an integer value.
n is the number of interim analyses so far
alpha is the desired overall size
phi optional Parameter referring to Power Family
OneOrTwoSidedBounds One-(OneOrTwoSidedBounds==1) or Two-sided bounds(OneOrTwoSidedBounds==2)
t is the vector of information times

Details

The use function, or type I error spending rate, corresponds to the
Alpha 1 star, Alpha 2 star and Alpha 3 star in Lan & DeMets(1983).

Value

probExit the vector of type I error (e.g. exit probabilities) spent at each analysis.

Note

This function is meant to be called in context of using groupseq

The parameter whatSpendingFunctionIsUsed is an integer value. At the moment there are 5 functions available - so only parameter from 1-5 will work:

Approximated by spending function:
(1) O'Brien-Fleming Type
(2) Pocock Type
(3) Power family: $α t^{phi}$
(4) Hwang-Shih-DeCani fammily

Classic Design:
(5) Pocock - the real Pocock Bounds

Author(s)

Roman Pahl

References

Lan & DeMets 1983 Biometrika http://www.biostat.wisc.edu/landemets/

See Also

groupseq, asHSdeCani, asPowerFamily asOBF, asPocock

Examples

## One-sided using O'Brien-Fleming Type
alphaByUseFunction(1,3,0.05,0,1,c(0.33,0.66,1.0))

## Two-sided using Power family: $\alpha t^{\phi}$ with $\phi$==1
alphaByUseFunction(3,3,0.05,1,2,c(0.33,0.66,1.0))

[Package GroupSeq version 1.0 Index]