Introduction

In this dissertation I will endeavour to evaluate the wide ranging concept of usability in the development and design of interactive systems in a methodical, concise and readable way. Despite each chapter relating to a separate topic, I will demonstrate that topics are often interrelated, intrinsically affected by one another and how, in combination, they influence the overall design of an interactive system.

As cited by Preece et al [1994] it is unfortunate that "information in books has to be presented sequentially". This is especially apparent when dealing with the subject of usability since it is composed of a wide ranging but inextricable and associated set of topics. In order to present this information in a more representative way, which truly reflects the nature of the concept, this dissertation contains many internal references. Indeed this piece, ideally, could have been written in a hypertext format.

In chapter 2, I will initially discuss what usability actually is and how, if possible, it can be measured. Then, in the subsequent chapters as a general theme, I will demonstrate how usability is interpreted and to what extent it is considered in respect to the development and design of interactive systems.

In chapter 3, I will describe the relatively recent increase in awareness of usability issues, why this has happened and the possible consequences if system usability is relegated to a low design priority.

In chapter 4, 5 & 6 I will evaluate, in detail, the various concepts within the topics of feedback, guessability, and user centred design. By illustrating with real examples, I will establish links between the theoretical and real worlds in order to assess the merits and weaknesses of relevant theories, notions and models.

Chapter 7 is a report on how user centred design is applied in practice in industry. My case study gives an account of the usability methodology used at Reuters, which not only involves their "customer centred design process" [RUG 1997] but also, incorporates their usability testing arrangements.

Finally, I conclude with chapter 8.