Description Usage Arguments Value References Examples
Finds the probability that a sequence of standard normal random variables z_1, z_2,…,z_m derived from a normal stochastic process with independent increments will cross a lower and and upper boundary.
1 |
a |
Lower boundary as a numeric vector of length m |
b |
Upper boundary as a numeric vector of length m |
t |
Information times as a numeric vector of length m |
int |
number of intervals that the Z-space is partitioned into for calculation purposes, increasing this will improve accuracy, this is also a numeric vector of length m |
Produces a numeric vector of length 2 m the first m components are the probability that the z_k will be less than a_k for some k≤ i and be less than b_k for all k ≤ i. The second m components are the probability that the z_k will be greater than b_k for some k≤ i and be greater than a_k for all k ≤ i.
Note that the last probability in the sequence is the overall significance level of a sequential design that uses a
and b
as upper and lower boundaries. To get power you subtract the μ √(t) from a
and b
where μ is the mean of z_m under the alternative hypothesis.
Schoenfeld, David A. "A simple algorithm for designing group sequential clinical trials." Biometrics 57.3 (2001): 972-974.
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