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

10 Golden Rules of Facilitation

Does Thinking Aloud Affect Where People Look?

What five users can tell you that 5000 cannot

How common are usability problems?

Does better usability increase customer loyalty?

Confidence Interval Calculator for a Completion Rate

How to Conduct a Usability test on a Mobile Device

Should you use 5 or 7 point scales?

97 Things to Know about Usability

8 Ways to Show Design Changes Improved the User Experience

10 Things to Know about Usability Problems

5 Examples of Quantifying Qualitative Data

A Brief History of the Magic Number 5 in Usability Testing

Nine misconceptions about statistics and usability

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

Quantifying the User Experience 2nd Ed.: Practical Statistics for User ResearchThe most comprehensive statistical resource for UX Professionals Buy on Amazon | |

Excel & R Companion to the 2nd Ed. of 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 | |

A Practical Guide to Measuring Usability72 Answers to the Most Common Questions about Quantifying the Usability of Websites and Software Buy on Amazon | Download |

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