NCSS PASS is one of the leading software tools for the design of medical trials and pharmaceutical or medical research in general. PASS provides the right methods for the power analysis of over 680 different statistical tests, confidence intervals and research scenarios.
Fast import of historical data – even in foreign data formats – and the simple interface help you focusing on the real problem: determining just the right sample size for your study.
Getting the right sample size involves just three steps:
 Choose the right study design from the navigator
 Enter the required parameters (typically: noise/standard deviation, relevant effect)
 Interpretation of results (Power, sample size)
That’s how easy NCSS PASS makes power calculation. All results will be visualized by highlevel scientific graphs. All graphs are highly customizable and will add an additional level of clarity to your reports.
NCSS PASS offers:
 Calculation of sample size and power
 Validated procedures
 Easy to learn, easy to use
 Professional graphics
 Helpful documentation as part of the output
 Easy export to all commonly used text editors
Recommended products
nQuery
What's New in PASS 2020?
PASS adds 38 new sample size procedures and 33 updated or improved procedures. Among the new and updated procedures are those for

 GroupSequential Tests for Hazard Rates, Means, and Proportions (Superiority and NonInferiority)
 GEE Tests for Means, Proportions, and Poisson Rates in a ClusterRandomized Design
 PostMarketing Surveillance for Poisson Rates
 Tests for Means and Proportions a SplitMouth Design
 Confidence Intervals in Cluster and Stratified Designs
 Tests for Means and Proportions in ClusterRandomized Designs
 Tests for Multiple Proportions and Poisson Rates
 Tests for One Exponential Hazard Rate
 Equivalence Tests for the Ratio of Two Means (Normal Data)
 Updated Randomization Lists (Block Randomization and Stratified Lists)
 Updated Conditional Power and Sample Size Reestimation of Means, Proportions, 2×2 CrossOver Designs, and Logrank Tests
 Updated OneWay ANOVA
 Updated Simplified Simulation Procedures for One Mean, Paired Means, Two Means, and MannWhitney Tests
 Updated McNemar Test
 Updated CochranMantelHaenszel Test
For the 11 new groupsequential sample size procedures in PASS , there are corresponding groupsequential analysis and samplesize reestimation procedures in NCSS
PASS  Power Analysis & Sample Size Software
PASS has been finetuned 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. PASS software performs power analysis and calculates sample sizes for over 680 statistical tests.
PASS Overview
PASS is a standalone system
Although it is integrated with NCSS, you do not have to own NCSS to run it. You can use it with any statistical software you want.
PASS is accurate
It has been extensively verified using books and reference articles. Proof of the accuracy of each procedure is included in the extensive documentation.
PASS comes with complete help system documentation
That contains tutorials, examples, annotated output, references, formulas, validation, and complete instructions on each procedure. All procedures are validated with published articles or books.
Choose PASS. It's more comprehensive, easiertouse, accurate, and less expensive than any other sample size program on the market.
Choosing A Procedure 
Enter The Values 
Further Information
 PASS and NCSS Homepage from the producer NCSS
 PASS complete documentation on the producers website
Trial version of the software PASS
The Producer (NCSS) provides a free trial version of the software. The trial version is 7day's long usable without any restrictions in it's features and/or functions. The license key for the trialversion can be upgraded to a full version, after purchasing an appropriate license. So there is no struggle with reinstallation or reregistrations of licenses.
You can access the trial version on the website of the producer, just click on the following link: http://www.ncss.com/download/pass/freetrial/
System Requirements for the Software PASS
In order to run PASS, your computer must meet the following minimum standards:
 Processor:
 450 MHz or faster processor
 32bit (x86) or 64bit (x64) processor
 RAM:
 256 MB (512 MB recommended)
 Operating Systems:
 Windows 10 or later
 Windows 8.1
 Windows 8
 Windows 7
 Windows Vista with Service Pack 2 or higher
 Windows Server 2016 or later
 Windows Server 2012 R2
 Windows Server 2012
 Windows Server 2008 SP2/R2
 Privileges:
 Administrative rights required during installation only
 Third Party Software:
 Microsoft .NET 4.6 (Comes preinstalled with Windows 10 or later and Windows Server
2016 or later. Installation required on Windows 8.1 or earlier and Windows Server
2012 R2 or earlier. For systems where .NET 4.6 installation is required, a .NET 4.6
download 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)
 Microsoft .NET 4.6 (Comes preinstalled with Windows 10 or later and Windows Server
 Hard Disk Space:
 220 MB for PASS (plus space for Microsoft .NET 4.6 if not already installed)
 Printer:
 Any Windowscompatible inkjet or laser printer
PASS on a Mac
A Windows emulator (such as Parallels) is required to run PASS 16 on a Mac.
What's New in PASS 2020?
PASS adds 38 new sample size procedures and 33 updated or improved procedures. Among the new and updated procedures are those for

 GroupSequential Tests for Hazard Rates, Means, and Proportions (Superiority and NonInferiority)
 GEE Tests for Means, Proportions, and Poisson Rates in a ClusterRandomized Design
 PostMarketing Surveillance for Poisson Rates
 Tests for Means and Proportions a SplitMouth Design
 Confidence Intervals in Cluster and Stratified Designs
 Tests for Means and Proportions in ClusterRandomized Designs
 Tests for Multiple Proportions and Poisson Rates
 Tests for One Exponential Hazard Rate
 Equivalence Tests for the Ratio of Two Means (Normal Data)
 Updated Randomization Lists (Block Randomization and Stratified Lists)
 Updated Conditional Power and Sample Size Reestimation of Means, Proportions, 2×2 CrossOver Designs, and Logrank Tests
 Updated OneWay ANOVA
 Updated Simplified Simulation Procedures for One Mean, Paired Means, Two Means, and MannWhitney Tests
 Updated McNemar Test
 Updated CochranMantelHaenszel Test
For the 11 new groupsequential sample size procedures in PASS , there are corresponding groupsequential analysis and samplesize reestimation procedures in NCSS
New Features in PASS
PASS adds over 55 new sample size procedures.
New Procedures
Logistic Regression
 Tests for the Odds Ratio in Logistic Regression with One Normal X (Wald Test)
 Tests for the Odds Ratio in Logistic Regression with One Normal X and Other Xs (Wald Test)
 Tests for the Odds Ratio in Logistic Regression with One Binary X and Other Xs (Wald Test)
Repeated Measures Slopes (GEE)
 GEE Tests for the Slope of Two Groups in a Repeated Measures Design (Continuous Outcome)
 GEE Tests for the Slope of Two Groups in a Repeated Measures Design (Binary Outcome)
 GEE Tests for the Slope of Two Groups in a Repeated Measures Design (Count Outcome)
 –
 GEE Tests for the Slope of Multiple Groups in a Repeated Measures Design (Continuous Outcome)
 GEE Tests for the Slope of Multiple Groups in a Repeated Measures Design (Count Outcome)
Repeated Measures TimeAveraged Differences (GEE)
 GEE Tests for the TAD of Two Groups in a Repeated Measures Design (Continuous Outcome)
 GEE Tests for the TAD of Two Groups in a Repeated Measures Design (Binary Outcome)
 GEE Tests for the TAD of Two Groups in a Repeated Measures Design (Count Outcome)
 –
 GEE Tests for the TAD of Multiple Groups in a Repeated Measures Design (Continuous Outcome)
 GEE Tests for the TAD of Multiple Groups in a Repeated Measures Design (Binary Outcome)
 GEE Tests for the TAD of Multiple Groups in a Repeated Measures Design (Count Outcome)
Hierarchical Design Comparisons using Mixed Models
 Mixed Models Tests for Two Means in a 2Level Hierarchical Design (Level2 Randomization)
 Mixed Models Tests for Two Means in a 2Level Hierarchical Design (Level1 Randomization)
 –
 Mixed Models Tests for Two Proportions in a 2Level Hierarchical Design (Level2 Randomization)
 Mixed Models Tests for Two Proportions in a 2Level Hierarchical Design (Level1 Randomization)
 –
 Mixed Models Tests for the Slope Difference in a 2Level Hierarchical Design with Fixed Slopes
 Mixed Models Tests for the Slope Difference in a 2Level Hierarchical Design with Random Slopes
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 Mixed Models Tests for Two Means in a 3Level Hierarchical Design (Level3 Randomization)
 Mixed Models Tests for Two Means in a 3Level Hierarchical Design (Level2 Randomization)
 Mixed Models Tests for Two Means in a 3Level Hierarchical Design (Level1 Randomization)
 –
 Mixed Models Tests for Two Proportions in a 3Level Hierarchical Design (Level3 Randomization)
 Mixed Models Tests for Two Proportions in a 3Level Hierarchical Design (Level2 Randomization)
 Mixed Models Tests for Two Proportions in a 3Level Hierarchical Design (Level1 Randomization)
 –
 Mixed Models Tests for the Slope Diff. in a 3Level Hier. Design with Fixed Slopes (Level2 Rand.)
 Mixed Models Tests for the Slope Diff. in a 3Level Hier. Design with Random Slopes (Level2 Rand.)
 Mixed Models Tests for the Slope Diff. in a 3Level Hier. Design with Fixed Slopes (Level3 Rand.)
 Mixed Models Tests for the Slope Diff. in a 3Level Hier. Design with Random Slopes (Level3 Rand.)
2×2 CrossOver Design – Odds Ratio
 Tests for the Odds Ratio of Two Proportions in a 2×2 CrossOver Design
 NonInferiority Tests for the Odds Ratio of Two Proportions in a 2×2 CrossOver Design
 Superiority by a Margin Tests for the Odds Ratio of Two Proportions in a 2×2 CrossOver Design
 Equivalence Tests for the Odds Ratio of Two Proportions in a 2×2 CrossOver Design
2×2 CrossOver Design – Proportion Difference
 Tests for the Difference of Two Proportions in a 2×2 CrossOver Design
 NonInferiority Tests for the Difference of Two Proportions in a 2×2 CrossOver Design
 Superiority by a Margin Tests for the Difference of Two Proportions in a 2×2 CrossOver Design
 Equivalence Tests for the Difference of Two Proportions in a 2×2 CrossOver Design
2×2 CrossOver Design – Ratio of Poisson Rates
 Tests for the Ratio of Two Poisson Rates in a 2×2 CrossOver Design
 NonInferiority Tests for the Ratio of Two Poisson Rates in a 2×2 CrossOver Design
 Superiority by a Margin Tests for the Ratio of Two Poisson Rates in a 2×2 CrossOver Design
 Equivalence Tests for the Ratio of Two Poisson Rates in a 2×2 CrossOver Design
2×2 CrossOver Design – Generalized Odds Ratio for Ordinal Data
 Tests for the Generalized Odds Ratio for Ordinal Data in a 2×2 CrossOver Design
 NonInferiority Tests for the Generalized Odds Ratio for Ordinal Data in a 2×2 CrossOver Design
 Superiority by a Margin Tests for the Gen. Odds Ratio for Ordinal Data in a 2×2 CrossOver Design
 Equivalence Tests for the Generalized Odds Ratio for Ordinal Data in a 2×2 CrossOver Design
Williams CrossOver Design – Pairwise Proportion Differences
 Tests for Pairwise Proportion Differences in a Williams CrossOver Design
 NonInferiority Tests for Pairwise Proportion Differences in a Williams CrossOver Design
 Superiority by a Margin Tests for Pairwise Proportion Differences in a Williams CrossOver Design
 Equivalence Tests for Pairwise Proportion Differences in a Williams CrossOver Design
Williams CrossOver Design – Pairwise Mean Differences
 Tests for Pairwise Mean Differences in a Williams CrossOver Design
 NonInferiority Tests for Pairwise Mean Differences in a Williams CrossOver Design
 Superiority by a Margin Tests for Pairwise Mean Differences in a Williams CrossOver Design
 Equivalence Tests for Pairwise Mean Differences in a Williams CrossOver Design
Multiple Correlated Proportions (StuartMaxwell Test)
 Tests for Multiple Correlated Proportions (StuartMaxwell Test)