Sample Size & Power

PASS software provides sample size tools for over 1100 statistical test and confidence interval scenarios - more than double the capability of any other sample size software. Each tool has been carefully validated with published articles and/or texts.

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.

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.

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.

System Requirements

Minimum System Requirements for PASS 2025

In order to run PASS 2025, your computer must meet the following minimum standards:

Processor:

• 450 MHz or faster processor
• 32-bit (x86) or 64-bit (x64) processor

RAM:

• 256 MB (512 MB recommended)

Operating Systems:

• Windows 11 or later
• Windows 10
• Windows 8.1
• Windows 8
• Windows 7

• Windows Server 2022 or later
• Windows Server 2019
• Windows Server 2016
• Windows Server 2012 R2
• Windows Server 2012
• Windows Server 2008 R2 SP1

Privileges:

Administrative rights required during installation only

Third Party Software:

Microsoft .NET 4.8 (Comes pre-installed with Windows 11 or later, Windows 10 (May 2019 Update) or later, and Windows Server 2022 or later. Installation required on Windows 10 (October 2018 Update (Version 1809)) or earlier and Windows Server 2019 or earlier. For systems where .NET 4.8 installation is required, a .NET 4.8 download helper will start automatically when you run the PASS setup file.)

Microsoft Visual C++ 2015-2022 Redistributable (x86) (For systems where Microsoft Visual C++ 2015-2022 Redistributable installation is required, a Microsoft Visual C++ 2015-2022 Redistributable installation helper will start automatically when you run the PASS setup file.)

Microsoft Windows Installer 3.1 or higher

Adobe Reader® 7 or higher (required for the Help System only)

Hard Disk Space:

450 MB for PASS (plus space for Microsoft .NET 4.8 and Microsoft Visual C++ 2015-2022 Redistributable if not already installed)

Printer:

Any Windows-compatible inkjet or laser printer

PASS 2025 on a Mac

A Windows emulator (such as Parallels) is required to run https://www.ncss.com/support/windows-on-a-mac/c/.