Quantifying the User Experience: Practical Statistics for User Research, Second Edition, provides practitioners and researchers with the information they need to confidently quantify, qualify, and justify their data. The book presents a practical guide on how to use statistics to solve common quantitative problems that arise in user research. It addresses questions users face every day, including, Is the current product more usable than our competition? Can we be sure at least 70 percent of users can complete the task on their first attempt? How long will it take users to purchase products on the website?

This book provides a foundation for statistical theories and the best practices needed to apply them. The authors draw on decades of statistical literature from human factors, industrial engineering, and psychology, as well as their own published research, providing both concrete solutions (Excel formulas and links to their own web calculators), along with an engaging discussion on the statistical reasons why tests work and how to effectively communicate results. Throughout this new edition, users will find updates on standardized usability questionnaires, a new chapter on general linear modeling (correlation, regression, and analysis of variance), with updated examples and case studies throughout.

• Completely updated to provide practical guidance on solving usability testing problems with statistics for any project, including those using Six Sigma practices
• Includes new and revised information on standardized usability questionnaires
• Includes a completely new chapter introducing correlation, regression, and analysis of variance
• Shows practitioners which test to use, why they work, and best practices for application, along with easy to use Excel formulas and web calculators for analyzing data
• Recommends ways for researchers and practitioners to communicate results to stakeholders in plain English

Review

"I will use this second edition as a reference when I need to find the latest thinking about UX measurement and when I teach statistics again it will be my first choice." --From the foreword by Joe Dumas, User Experience Consultan

"Sauro and Lewis are the acknowledged leaders in the quantitative assessment of usability, and their combined wisdom is ably reflected in the second edition of this book. Serious practitioners of usability science will find this book a valuable addition to the highly qualitative texts that are currently available." --Philip Kortum, Rice University

"To-Do list for the UX Field to become a true discipline: • Develop a rich collection of user-centered design methods [CHECK].• Drive understanding of the importance of UX into most design/development teams [CHECK]. • Advocate for and educate about how to implement a serious, empirical, practical approach to gathering and analyzing user data. [Thanks to the career-long work of Sauro and Lewis, culminating in this book, we can now say . . . CHECK.]" – Randolph G. Bias, Professor, School of Information, The University of Texas at Austin

Table of Contents

1.Introduction and How to Use This Book

2.Quantifying User Research

3.How Precise Are Our Estimates? Confidence Intervals

4.Did We Meet or Exceed Our Goal?

5.Is There a Statistical Difference Between Designs?

6.What Sample Sizes Do We Need? Part 1: Summative Studies

7.What Sample Sizes Do We Need? Part 2: Formative Studies

8.Standardized Usability Questionnaires

9.Six Enduring Controversies in Measurement and Statistics

10.An Introduction to Correlation, Regression, and ANOVA

11Wrapping Up

Appendix: A Crash Course in Fundamental Statistical Concepts

Subject Index

About the Authors

Dr. Jeff Sauro is a six-sigma trained statistical analyst and founding principal of MeasuringU, a customer experience research firm based in Denver. For over fifteen years he’s been conducting usability and statistical analysis for companies such as Google, eBay, Walmart, Autodesk, Lenovo and Drobox or working for companies such as Oracle, Intuit and General Electric.Jeff has published over twenty peer-reviewed research articles and five books, including Customer Analytics for Dummies. He publishes a weekly article on user experience and measurement online at measuringu.com.

Jeff received his Ph.D in Research Methods and Statistics from the University of Denver, his Masters in Learning, Design and Technology from Stanford University, and B.S. in Information Management & Technology and B.S. in Television, Radio and Film from Syracuse University. He lives with his wife and three children in Denver, CO.

Dr. James R. (Jim) Lewis is a senior human factors engineer (at IBM since 1981) with a current focus on the measurement and evaluation of the user experience. He is a Certified Human Factors Professional with a Ph.D. in Experimental Psychology (Psycholinguistics), an M.A. in Engineering Psychology, and an M.M. in Music Theory and Composition. Jim is an internationally recognized expert in usability testing and measurement, contributing (by invitation) the chapter on usability testing for the 3rd and 4th editions of the Handbook of Human Factors and Ergonomics, presenting tutorials on usability testing and metrics at various professional conferences, and serving as the keynote speaker at HCII 2014. He was the lead interaction designer for the product now regarded as the first smart phone, the Simon, and is the author of Practical Speech User Interface Design.

Jim is an IBM Master Inventor Emeritus with 88 patents issued to date by the US Patent Office. He serves on the editorial board of the International Journal of Human-Computer Interaction, is co-editor in chief of the Journal of Usability Studies, and is on the scientific advisory board of the Center for Research and Education on Aging and Technology Enhancement (CREATE). He is a member of the Usability Professionals Association (UPA), the Human Factors and Ergonomics Society (HFES), the ACM Special Interest Group in Computer-Human Interaction (SIGCHI), past-president of the Association for Voice Interaction Design (AVIxD), and is a 5th degree black belt and certified instructor with the American Taekwondo Association (ATA).