Sealed envelope - Power (Sample Size) Calculators

Use these calculators for clinical trials including superiority, equivalence and non-inferiority trials.

What the calculators offer

This website provides on-line tools to estimate the sample size needed for a clinical trial. Sample size calculations are supported for the following trial designs and outcome types:

The information required as input from the user is clearly identified, as is the output generated by the program. The program does not have a calculator for time-to-event outcomes. The calculator does not provide the option of calculating the power, only the sample size. However, the program clearly explains the difference between the different designs (superiority, equivalence, non-inferiority), and provides references and the citation for the service.

Who it's for

Clinical investigators, statisticians

Who created it

This site is run by sealed envelope TM , a British company that provides access to online software applications for randomizing patients into clinical trials and recording their case report form data.

About Us

The Biostats4you website was developed to serve medical and public health researchers and professionals who wish to learn more about biostatistics. The site contains carefully selected and reviewed training materials especially suited for a non-statistician audience. This site is being developed and maintained by members of the Biostatistics, Epidemiology and Research Design Special Interest Group (BERD SIG) of the Association for Clinical and Translational Science (ACTS). The external links on this site are checked periodically to be sure they still work. They are also re-reviewed on an ongoing basis. However, the links are not under the auspices of the BERD SIG or ACTS.

Contact

Suggest additional topics or resources, alert us of problems, or share suggestions for improvement:
[email protected]

The site is hosted by the University of Minnesota’s Clinical and Translational Science Institute (CTSI), led by their BERD group, the Biostatistical Design and Analysis Center (BDAC). CTSI is supported by the National Institutes of Health's National Center for Advancing Translational Sciences, grant UL1TR002494

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