NCSS PASS 2025 v25.0.2

PASS software provides sample size calculators for over 1,200 statistical test scenarios and confidence intervals - twice the capabilities of any other sample size calculator. Each tool has been carefully validated with published articles and/or literature.

PASS has been refined for over 25 years and is now the leading sample size calculator software choice for clinical trials, pharmaceuticals, and other medical research. It has also become a mainstay in all other fields where sample size needs to be calculated or evaluated.

Getting sample size in PASS

In PASS, you can estimate the sample size for a statistical test or confidence interval in just a few short steps. If you need guidance at any step, PASS has excellent documentation, free training videos, and you can contact our team of PhD statisticians.

Select a procedure

Finding a sample size procedure is easy using the drop-down menu, procedure search, or category tree.

Entering Values

The sample size procedure tools are easy to use and have built-in help messages for every option.

Zoom in on the infographic to see descriptions of how PASS helps you enter the appropriate values ​​into the sample size procedure tool.

Ready-to-use output

Once the PASS procedure is run, the sample size results and corresponding graphs will be displayed in the output window. The sample size or power curve can be clicked to display in a separate window for viewing or saving.

Output navigation is easy with the output navigation tree. The output format makes it easy to view, copy and paste, or save. Multiple output runs can be sent to the output library for saving or to compare sample size analyses.