GroupSeq (version 1.0)

computeConfidenceIntervall: 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

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