You’re being asked to quantify usability improvements with statistics. But even with a background in statistics, you are hesitant to statistically analyze the data, as you may be unsure about which statistical tests to use and have trouble defending the use of the small test sample sizes associated with usability studies. This book is about providing a practical guide on how to use statistics to solve common quantitative problems arising in user research. It addresses common questions you face every day. This book shows you which test to use, and how provide a foundation for both the statistical theory and best practices in applying them.