Group Sequential Design Probabilities - With Graphical User Interface R package GroupSeq version 1.4.3 CRAN Task View: ClinicalTrials (https://CRAN.R-project.org/view=ClinicalTrials) CRAN Task View: ExperimentalDesign (https://CRAN.R-project.org/view=ExperimentalDesign) Computes probabilities related to group sequential designs for normally distributed test statistics. Enables to derive critical boundaries, power, drift, and confidence intervals of such designs. Supports the alpha spending approach by Lan-DeMets (1994) <doi:10.1002/sim.4780131308>. Software Imports: tcltk, tcltk2, mvtnorm Suggests: knitr, tinytest, rmarkdown, ggplot2, gridExtra Roman Pahl <roman.pahl@gmail.com> Comprehensive R Archive Network (CRAN) Roman Pahl [aut, cre] GPL-3 2024-02-03 application/tgz https://CRAN.R-project.org/package=GroupSeq doi:10.32614/CRAN.package.GroupSeq