Jeff Sauro • December 3, 2007

Enter a z-critical value and get the area under the normal curve (a percentage). Selecting two-sided provides the area above Z and below -Z. Selecting one side provides the area only above or below the Z-value. See also the interactive Graph of the Standard Normal Curve. To convert a percentage into a Z-Score use the Percentile to Z-Score Calculator.Download this calculator in an excel file or take a Crash course in Z-scores

3 Days of Hands-On Training on UX Methods, Metrics and Analysis

Denver: Aug. 17-19 2016

15 Mobile UX Facts and Insights for 2016

5 Ways to Use the System Usability Scale (SUS)

97 Things to Know about Usability

Confidence Interval Calculator for a Completion Rate

8 Ways to Show Design Changes Improved the User Experience

10 Things to Know about Usability Problems

Why you only need to test with five users (explained)

Nine misconceptions about statistics and usability

5 Examples of Quantifying Qualitative Data

How to Conduct a Usability test on a Mobile Device

How common are usability problems?

A Brief History of the Magic Number 5 in Usability Testing

Should you use 5 or 7 point scales?

What five users can tell you that 5000 cannot

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Customer Analytics for DummiesA guidebook for measuring the customer experience Buy on Amazon | |

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Excel & R Companion to Quantifying the User ExperienceDetailed 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 ScaleBackground, Benchmarks & Best Practices for the most popular usability questionnaire Buy on Amazon | Download | |

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