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Confirmatory Adaptive Clinical Trial Design, Simulation, and Analysis.

Functional Range

  • Fixed sample design and designs with interim analysis stages
  • Sample size and power calculation for
    • means (continuous endpoint)
    • rates (binary endpoint)
    • survival trials with flexible recruitment and survival time options
    • count data
  • Simulation tool for means, rates, and survival data
    • Assessment of adaptive sample size/event number recalculations based on conditional power
    • Assessment of treatment selection strategies in multi-arm trials
  • Adaptive analysis of means, rates, and survival data
  • Adaptive designs and analysis for multi-arm trials
  • Adaptive analysis and simulation tools for enrichment design testing means, rates, and hazard ratios
  • Automatic boundary recalculations during the trial for analysis with alpha spending approach, including under- and over-running


Install the latest CRAN release via

Development version

To use a feature from the development version, you can install the development version of rpact from GitHub.

# install.packages("pak")


The documentation is hosted at


The vignettes are hosted at

The rpact user group

The rpact project has an active user group consisting of decision-makers and users from the pharmaceutical industry and CROs, who meet regularly and, e.g., discuss best practices.

We invite you to be part of the rpact user group: benefit from know-how, shape open source development in Pharma!

Use on corporate computer systems

Please contact us to learn how to use rpact on FDA/GxP-compliant validated corporate computer systems and how to get a copy of the formal validation documentation that is customized and licensed for exclusive use by your company, e.g., to fulfill regulatory requirements. The validation documentation contains the personal access data for performing the installation qualification with testPackage().


  • rpact is a comprehensive validated1 R package for clinical research which
    • enables the design and analysis of confirmatory adaptive group sequential designs
    • is a powerful sample size calculator
    • is a free of charge open-source software licensed under LGPL-3
    • particularly, implements the methods described in the recent monograph by Wassmer and Brannath (2016)

For more information please visit

  • RPACT is a company which offers
    • enterprise R/Shiny software development services
    • technical support for the rpact package
    • consultancy and user training for scientists using R
    • validated software solutions and R package development for clinical research

For more information please visit