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.Getting Started Finding the Right Sample Size

The Essentials of a Contextual Inquiry

8 Ways to Show Design Changes Improved the User Experience

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

The Five Most Influential Papers in Usability

Confidence Interval Calculator for a Completion Rate

97 Things to Know about Usability

What five users can tell you that 5000 cannot

A Brief History of the Magic Number 5 in Usability Testing

Does better usability increase customer loyalty?

10 Things to Know about Usability Problems

Nine misconceptions about statistics and usability

How common are usability problems?

5 Examples of Quantifying Qualitative Data

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

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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