Performing computations related to groupseqential boundaries.
Description
The computations are done with the alpha spending approach. Therefore
interim analyses need not to be equally spaced, and their number need not to be specified in advance.
It is appropriate for any trial based on normally distributed test statistics with independent increments,
survival studies, and certain longitudinal designs.
Among other things it computes boundaries, power, drift and confidence intervals.
The package provides this in a GUI and user has option of graphical output of the results
and saving them into .html files.