drift
(Package: ldbounds) :
Drift and Probabilities for Group Sequential Boundaries
'drift' calculates drift (effect), confidence interval for drift, or power and other probabilities given drift for specified group sequential boundaries for interim analyses of accumulating data in clinical trials.
bounds
(Package: ldbounds) :
Group Sequential Boundaries Using Spending Functions
'bounds' determines group sequential boundaries for interim analyses of accumulating data in clinical trials using the Lan-DeMets alpha spending function method. These can be used as guidelines for early stopping of the trial.