Measuring Usability
Quantitative Usability, Statistics & Six Sigma by Jeff Sauro

Calculators

A/B Test Calculator

By: Jeff Sauro • April 17, 2012

Compare two independent proportions for A/B testing or comparing completion rates or conversion rates for small and large sample sizes. Uses the N-1 Two proportion test and Fisher Exact test to generate p-values.[Read More]

Sample Size Calculator for Discovering Problems in a User Interface

By: Jeff Sauro • October 1, 2006

Use this calculator to determine the number of users you'd need to test given the probability of detecting a problem. If the probability of detecting the problem is unknown, this calculator also allows you to estimate the problem occurrence (p) from sample data.[Read More]

Graph and Calculator for Confidence Intervals for Task Times

By: Jeff Sauro • February 6, 2006

Visualizing your task time data is an essential step in understanding its distribution and computing accurate confidence intervals. This calculator creates a dot-plot of your task times, transforms the raw data to adjust for non-normality and computes the intervals.[Read More]

Confidence Interval Calculator for a Completion Rate

By: Jeff Sauro • October 1, 2005

If you've wanted to provide a confidence interval around a small sample completion rate but just didn't have time to do the math, this calculator does the work for you.[Read More]

Sample Size Calculator for a Completion Rate

By: Jeff Sauro • January 4, 2008

Use this interactive calculator to understand how the sample size changes will affect the confidence interval around a completion rate.[Read More]

Z-Score to Percentile Calculator

By: Jeff Sauro • December 3, 2007

Look up the area under the normal curve (1 or two-sided areas) from a standard score (Z-score).[Read More]

Percentile to Z-Score Calculator

By: Jeff Sauro • December 4, 2007

Enter the area under the normal curve (a proportion between 0 & 1) and get the Z-critical value.[Read More]

Interactive Graph of the Standard Normal Curve

By: Jeff Sauro • December 14, 2007

Use this interactive normal curve to understand how the z-score and the area of the curve are related. Offers both one and two-sided options.[Read More]

One Sample Proportion Calculator

By: Jeff Sauro • May 30, 2008

[Read More]

Compare 2 Small Sample Completion Rates (Fisher Exact Test)

By: Jeff Sauro • June 5, 2009

Used for comparing 2 small sample binary completion rates (it uses a statistical test called the Fisher Exact Test)[Read More]

Confidence Interval Calculator

By: Jeff Sauro • March 21, 2012

Compute confidence intervals around continuous data using either raw or summary data.[Read More]

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About Jeff Sauro

Jeff Sauro is the founding principal of Measuring Usability LLC, a company providing statistics and usability consulting to Fortune 1000 companies.
He is the author of over 20 journal articles and 4 books on statistics and the user-experience.
More about Jeff...

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Jeff's Books

Quantifying the User Experience: Practical Statistics for User ResearchQuantifying the User Experience: Practical Statistics for User Research

The most comprehensive statistical resource for UX Professionals

Buy on Amazon

Excel & R Companion to Quantifying the User ExperienceExcel & R Companion to Quantifying the User Experience

Detailed Steps to Solve over 100 Examples and Exercises in the Excel Calculator and R

Buy on Amazon | Download

A Practical Guide to the System Usability ScaleA Practical Guide to the System Usability Scale

Background, Benchmarks & Best Practices for the most popular usability questionnaire

Buy on Amazon | Download

A Practical Guide to Measuring UsabilityA Practical Guide to Measuring Usability

72 Answers to the Most Common Questions about Quantifying the Usability of Websites and Software

Buy on Amazon | Download

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