Stipulates alpha spending according to the O'Brien-Fleming
spending function in the Lan-Demets boundary construction method. Its
intended purpose is in constructing calls to
An object of class
spending.function which is really a list
with the following components. The print method displays the original
Gives the spending function type, which is the character string "ObrienFleming"
returns the call
The print method returns the call by default
see references under
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## example 1: what is the result of calling a spending function ## A call to 'ObrienFleming' just returns the call ObrienFleming() ## but really its value is a list with a component named ## 'type' equal to "ObrienFleming" and a component named ## 'call' equal to the call. names(ObrienFleming) ObrienFleming()$type ObrienFleming()$call ## example 2: ...But the intended purpose of the spending functions its ## intended purpose 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=ObrienFleming), FutilityBoundary=LanDemets(alpha=0.10, spending=Pocock), drift=drift)
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