seqCI: Confidence interval with the last Z-value for the group sequential design
Description
Confidence interval with given upper bounds, time of tests, the last Z-value, and confidence level.
Usage
seqCI(bi, ti, Zval, conf.level=0.95)
Value
confidence interval of Z-value for the given confidence level.
Arguments
bi
upper bound z-values
ti
times for test. These should be [0, 1].
Zval
the last z-value from the observed data. This is not necessarily the planned final Z-value.
conf.level
confidence level
Author
Kyun-Seop Bae k@acr.kr
Details
It calculates confidence interval with given upper bounds, time of tests, the last Z-value, and confidence level. It assumes two-side test. mvtnorm::pmvt (with noncentrality) is better than pmvnorm in calculating power, sample size, and confidence interval. But, Lan-DeMets used multi-variate normal rather than multi-variate noncentral t distributionh. This function followed Lan-DeMets for the consistency with previous results. For the theoretical background, see the reference.
References
Reboussin DM, DeMets DL, Kim K, Lan KKG. Computations for group sequential boundaries using the Lan-DeMets function method. Controlled Clinical Trials. 2000;21:190-207.