Drift: Drift defined by Lan and DeMets for Group Sequential Design
In sasLM: 'SAS' Linear Model
Drift R Documentation
Drift defined by Lan and DeMets for Group Sequential Design
Description
Calculate the drift value with given upper bounds (z-values), times of test, and power.
Usage
Drift(bi, ti=NULL, Power=0.9)
Arguments
bi
upper bound z-values
ti
times of test. These should be in the range of [0, 1]. If omitted, equal intervals are assumed.
Power
target power at the final test
Details
It calculates the drift value with given upper bound z-values, times of test, and power. If the times of test are not given, equal intervals are assumed. mvtnorm::pmvt (with noncentrality) is better than pmvnorm in calculating power and sample size. However, Lan-DeMets used the multivariate normal rather than the multivariate noncentral t distribution. This function follows Lan-DeMets for consistency with previous results.
Value
Drift value for the given condition
Author(s)
Kyun-Seop Bae k@acr.kr
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.
Examples
Drift(seqBound(ti=(1:5)/5)[, "up.bound"])
sasLM documentation built on June 15, 2026, 9:07 a.m.
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| Drift | R Documentation |
Drift defined by Lan and DeMets for Group Sequential Design
Description
Calculate the drift value with given upper bounds (z-values), times of test, and power.
Usage
Drift(bi, ti=NULL, Power=0.9)
Arguments
bi |
upper bound z-values |
ti |
times of test. These should be in the range of [0, 1]. If omitted, equal intervals are assumed. |
Power |
target power at the final test |
Details
It calculates the drift value with given upper bound z-values, times of test, and power. If the times of test are not given, equal intervals are assumed. mvtnorm::pmvt (with noncentrality) is better than pmvnorm in calculating power and sample size. However, Lan-DeMets used the multivariate normal rather than the multivariate noncentral t distribution. This function follows Lan-DeMets for consistency with previous results.
Value
Drift value for the given condition
Author(s)
Kyun-Seop Bae k@acr.kr
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.
Examples
Drift(seqBound(ti=(1:5)/5)[, "up.bound"])
R Package Documentation
Browse R Packages
We want your feedback!
Note that we can't provide technical support on individual packages. You should contact the package authors for that.
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