Jeff Sauro • February 6, 2006

This calculator takes raw task times, transforms them using the Natural Logarithm and computes a confidence interval. The values are displayed in the dot-plots graph below. You can also download an excel version of this calculator.3 Days of Hands-On Training on User Experience Methods, Metrics and Analysis.Learn More

28 Resources for Getting Started In UX

What To Do When You Can't Run a Usability Test

10 Methods To Improve the Customer Experience

Should the Net Promoter Score Go? 5 Common Criticisms Examined

Does better usability increase customer loyalty?

10 Things to Know about Usability Problems

What five users can tell you that 5000 cannot

How to Conduct a Usability test on a Mobile Device

Should you use 5 or 7 point scales?

A Brief History of the Magic Number 5 in Usability Testing

Confidence Interval Calculator for a Completion Rate

97 Things to Know about Usability

Nine misconceptions about statistics and usability

The Five Most Influential Papers in Usability

How common are usability problems?

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

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

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 | |

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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