computeConfidenceIntervall {GroupSeq}R Documentation

Computes confidence intervals

Description

Computes confidence intervals, see Kim & DeMets 87. Given n interim analyses, bounds for the first n-1 and the standardized statistic for the nth, the function finds drift parameters satisfying confidence limit equations.

Usage

computeConfidenceIntervall(confidenceLevel, Zvalue, n, t, t2, lowerBounds, upperBounds, nMax)

Arguments

confidenceLevel is confidence level.
Zvalue is the Z statistic at the most recent analysis.
n is the number of analyses.
t is the vector of analysis time point on (0,1).
t2 is the second or information time scale, for covariances
lowerBounds is the vector of lower bounds (standardized).
upperBounds is the vector of upper bounds (standardized).
nMax maximum Number of interim analyses (default: nMax=25)

Value

confidenceLimit the calculated confidence interval

Note

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

Author(s)

Roman Pahl

References

Kim & DeMets 1987 Biometrics http://www.biostat.wisc.edu/landemets/

See Also

groupseq, qnorm computeDrift

Examples

## fictious example
computeConfidenceIntervall(0.05, 1.7, 2, c(0.5,1.0), c(0.5,1.0), c(-1,0), c(1,2), 25)
## with following result:
# [1] 1.115315 1.264942

[Package GroupSeq version 1.0 Index]