User engagement refers to the quality of the user experience that emphasizes the positive
aspects of interacting with an online application and in particular the desire to use that
application longer and repeatedly. User engagement is a key concept in the design of online
applications (whether for desktop tablet or mobile) motivated by the observation that
successful applications are not just used but are engaged with. Users invest time attention
and emotion in their use of technology and seek to satisfy pragmatic and hedonic needs.
Measurement is critical for evaluating whether online applications are able to successfully
engage users and may inform the design of and use of applications. User engagement is a
multifaceted complex phenomenon this gives rise to a number of potential measurement
approaches. Common ways to evaluate user engagement include using self-report measures e.g.
questionnaires observational methods e.g. facial expression analysis speech analysis
neuro-physiological signal processing methods e.g. respiratory and cardiovascular
accelerations and decelerations muscle spasms and web analytics e.g. number of site visits
click depth. These methods represent various trade-offs in terms of the setting (laboratory
versus ``in the wild'') object of measurement (user behaviour affect or cognition) and scale
of data collected. For instance small-scale user studies are deep and rich but limited in
terms of generalizability whereas large-scale web analytic studies are powerful but negate
users' motivation and context. The focus of this book is how user engagement is currently being
measured and various considerations for its measurement. Our goal is to leave readers with an
appreciation of the various ways in which to measure user engagement and their associated
strengths and weaknesses. We emphasize the multifaceted nature of user engagement and the
unique contextual constraints that come to bear upon attempts to measure engagement in
different settings and across different user groups and web domains. At the same time this
book advocates for the development of ``good'' measures and good measurement practices that
will advance the study of user engagement and improve our understanding of this construct
which has become so vital in our wired world.
