PwrGSD: Ch05-Pocock – R documentation

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Ch05-Pocock

The Pocock Alpha Spending Function

Description

Stipulates alpha spending according to the Pocock spending function in the Lan-Demets boundary construction method. Its intended purpose is in constructing calls to GrpSeqBnds and PwrGSD.

Usage

Pocock()

Value

An object of class spending.function

`type`	Gives the spending function type, which is the character string "Pocock"
`call`	returns the call

Note

The print method returns the call by default

Author(s)

Grant Izmirlian

References

see references under PwrGSD

Examples

## example 1: what is the result of calling a spending function

    ## A call to 'Pocock' just returns the call
    Pocock()

    ## but really its value is a list with a component named
    ## 'type' equal to "Pocock" and a component named
    ## 'call' equal to the call.
    names(Pocock)

    Pocock()$type

    Pocock()$call

## example 2: ...But the intended purpose of the spending functions is
## in constructing calls to 'GrpSeqBnds' and to 'PwrGSD':
     

    frac <- c(0.07614902,0.1135391,0.168252,0.2336901,0.3186155,
              0.4164776,0.5352199,0.670739,0.8246061,1)
    drift <- c(0.3836636,0.5117394,0.6918584,0.8657705,1.091984,
               1.311094,1.538582,1.818346,2.081775,2.345386)

    test <- GrpSeqBnds(frac=frac, EfficacyBoundary=LanDemets(alpha=0.05, spending=Pocock),
                       FutilityBoundary=LanDemets(alpha=0.10, spending=ObrienFleming),
                       drift=drift)

PwrGSD

Power in a Group Sequential Design

v2.3.3

GPL (>= 2)

Authors

Grant Izmirlian <izmirlig@mail.nih.gov>

Initial release