Sample Size & Power

PASS software provides sample size tools for over 680 statistical test and confidence interval scenarios. Each tool has been carefully validated with published articles and/or texts.

Get to know PASS by downloading a free trial, viewing the video to the right, or exploring this website.

PASS comes complete with integrated documentation and PhD statistician support.

PASS has been fine-tuned for over 20 years, and has become the leading sample size software choice for clinical trial, pharmaceutical, and other medical research. It has also become a mainstay in all other fields where sample size calculation or evaluation is needed.

Obtaining A Sample Size In PASS

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

 Enlarge Infographic

Choosing A Procedure

Finding the sample size procedure is easy using the drop-down menu, the procedure search, or the category tree. Watch a short video to learn how to select your desired procedure in PASS.

 Enlarge Infographic

Enter The Values

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

Enlarge the infographic to see the descriptions of the ways that PASS helps you to enter the proper values in a sample size procedure tool. You can also watch this video to see an example of using a procedure window in PASS.

 Enlarge Infographic

Ready to Use Output

When a PASS procedure is run, the sample size results and corresponding plots are displayed in the output window. The sample size or power curves can be clicked to be shown in a separate window for viewing or saving.

Navigation of the output is easy with the output navigation tree. The format of the output makes it easy to be viewed, copied and pasted, or saved. Multiple output runs can be sent to the output gallery for saving or for comparing sample size analyses.

To take a video tour of the output window in PASS, click here.

 Enlarge Infographic

Publications Citing PASS

International Urogynecology Journal
Clinical and Experimental Pharmacology and Physiology
Annals of Oncology
The American Journal of Clinical Nutrition
International Orthopaedics
Journal of Veterinary Internal Medicine
Journal of Anesthesia
Journal of Cardiology
International Journal of Rheumatic Diseases
Cardiothoracic and Vascular Anesthesia
Journal of Advanced Nursing
Gastrointestinal Endoscopy
Experimental & Clinical Cardiology
American Heart Journal
American Journal of Transplantation
Annals of Internal Medicine
American Journal of Surgery

Start Your Free 7 Day Trial Now Buy Now

“I’ve used NCSS since 1986 and PASS since 1997. The utility, precision, documentation, output and ease-of-use of your products are the best in the business. Thank you!”

Tim Gohmann, Ph.D.

"PASS 13 is fantastic! Better than my new dishwasher and microwave combined."

Dr. Barbara Tabachnick, CSUN, Author