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.


Changes in 1.3.3 (2015-07-08)

Code revision:

  • moved all alpha spending functions into a single file
  • removed 'require(tcltk) dependency' and added NAMESPACE imports accordingly
  • removed special (non-UTF8) characters and trimmed whitespaces


  • Fixed broken link to Lan-DeMets program in help file
  • New maintainer email address: [email protected]
  • Shortened 'Description' and fixed title case in 'Title' field.

Changes in 1.3.2 (2014-01-10)


  • Fixed error occuring with task -3- when user had chosen "Asymmetric" bounds


  • Changed maintainer email address to [email protected]
  • Revised "Title" and general "Description"
  • Revised the details section of the manual

Reference manual

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