The computations are done via the alpha spending approach i.e. 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 critical boundaries for various spending functions and for prespecified
power and drift. Confidence intervals are also obtained.
The package provides this in a GUI and users have option of graphical output of the results
and/or saving desings into .html-file tables allowing further processing.

Performing computations related to group sequential designs.
The computations are done via the alpha spending approach
i.e. interim analyses need not to be equally spaced, and their
number need not to be specified in advance.

A GUI-based program to compute probabilities regarding group
sequential designs.
The package provides a Tcl/Tk-based graphical user interface. It
enables the construction of group sequential designs based on normally
distributed test statistics, and particularly to compute critical
boundaries, power, drift, and confidence intervals for such designs. All
computations are done via the alpha spending approach by Lan-DeMets.
Various alpha spending functions are made available to the user for this
purpose.

A GUI-Based Program to Compute Probabilities Regarding Group
Sequential Designs
A graphical user interface to compute group sequential designs
based on normally distributed test statistics, particularly critical
boundaries, power, drift, and confidence intervals of such designs. All
computations are based on the alpha spending approach by Lan-DeMets with
various alpha spending functions being available to choose among.

person("Roman", "Pahl",
email = "roman.pahl@gmail.com", role = c("aut", "cre"))

The computations are done via the alpha spending approach i.e. interim
analyses need not to be equally spaced, and their number need not to be specified in advance.