User Experience Foundations

6 MEASURING USABILITY

Civilization advances by extending the number of important operations which we can perform without thinking about them.

Alfred North Whitehead (1911)

INTRODUCTION

This chapter describes how to build a design around objectively measurable concepts so that it can be progressively evaluated and improved using an iterative process. We examine the definition of usability and its subsidiary components of effectiveness, accuracy, completeness, efficiency and satisfaction. We see how these, together with the definition of the context of use, can form the basis for a series of experiments that will guide development. We introduce the Build–Measure–Learn loop and the idea of validated learning. To conclude, we show how split ...