DOI: 10.1016/S0306-4573(98)00065-X / There was a proliferation of electronic information sources and search engines in the 1990s. Many of these information sources became available through the ubiquitous interface of the Web browser. Diverse information sources became accessible to information professionals and casual end users alike. Much of the information was also hyperlinked, so that information could be explored by browsing as well as searching. While vast amounts of information were now just a few keystrokes and mouseclicks away, as the choices multiplied, so did the complexity of choosing where and how to look for the electronic information. Much of the complexity in information exploration at the turn of the twenty-first century arose because there was no common cataloguing and control system across the various electronic information sources. In addition, the many search engines available differed widely in terms of their domain coverage, query methods, and efficiency. Meta-search engines were developed to improve search performance by querying multiple search engines at once. In principle, meta-search engines could greatly simplify the search for electronic information by selecting a subset of first-level search engines and digital libraries to submit a query to based on the characteristics of the user, the query/topic, and the search strategy. This selection would be guided by diagnostic knowledge about which of the first-level search engines works best under what circumstances. Programmatic research is required to develop this diagnostic knowledge about first-level search engine performance. This paper introduces an evaluative framework for this type of research and illustrates its use in two experiments. The experimental results obtained are used to characterize some properties of leading search engines (as of 1998). Significant interactions were observed between search engine and two other factors (time of day, and Web domain). These findings supplement those of earlier studies, providing preliminary information about the complex relationship between search engine functionality and performance in different contexts. While the specific results obtained represent a time-dependent snapshot of search engine performance in 1998, the evaluative framework proposed should be generally applicable in the future.

The term â hypertextâ evokes many images (e.g., nodes and links, semantic webs, non-linear access and so forth) but perhaps one of the most common is that of users struggling to find their way around a complex information space. As a result, navigation has become a subject of great interest to many researchers in the field. In this chapter we will discuss navigation through hypertext in terms of its relevance as a concept as much as its presence as an issue and try to draw lessons for design and research from the psychological work that has been carried out on navigation in physical space. We will attempt to show that while relevant to hypertext, discussion of navigation is prone to difficulty when researchers and designers misapply arguments and evidence from the physical domain to the semantic domain.

This position paper argues that the Web 2.0 phenomenon is an important object of study for information systems research, and that a social informatics approach to understanding Web 2.0 is particularly relevant and useful. We discuss Wikipedia as an example of empirical research on Web 2.0 that can help bridge the divide between academic and popular discourse on new technology movements.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. (2001) Usability evaluation. In W. Karwowski (ed.) Encyclopedia of Human Factors and Ergonomics, London: Taylor and Francis. Introduction: Usability is a measure of interface quality that refers to the effectiveness, efficiency and satisfaction with which users can perform tasks with a tool. Evaluating usability is now considered an essential part of the system development process and a variety of methods and have been developed to support the human factors professional in this work.

This position paper argues that the Web 2.0 phenomenon is an important object of study for information systems research, and that a social informatics approach to understanding Web 2.0 is particularly relevant and useful. We discuss Wikipedia as an example of empirical research on Web 2.0 that can help bridge the divide between academic and popular discourse on new technology movements.

This item is not the definitive copy. Please use the following citation when referencing this material: McKnight, C., Dillon, A. and Richardson, J. (1992) Hypermedia. In A. Kent (Ed.) Encyclopedia of Library and Information Science, Vol. 50, New York: Marcel Dekker, 226-255. Overview: The field of hypertext/hypermedia has mushroomed so much in the last five years that an article such as this cannot hope to be all-embracing. Rather, what we will do is provide a perspective on hypertext/hypermedia while offering guidance to the published literature. The perspective we give is essentially user-centred since we believe that ultimately it is user issues which will determine the success or failure of any technology. We begin with a brief introduction and history then draw together some of the relevant research which has a bearing on hypertext/hypermedia usability. Some of this research has been conducted specifically in the field of hypertext but some general human-computer interaction research also needs to be considered. We look briefly at some of the issues involved in creating hypertexts and also at some of the claims made for hypertext. Finally, we attempt to see what the future holds for hypertext and offer a list of further reading.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A., Richardson, J. and McKnight, C. (1989) The human factors of journal usage and the design of electronic text. Interacting with Computers, 1(2), 183- 189. Abstract: The present paper reports on a study of journal usage amongst human factors researchers. The aim of the study was to shed light on how journals are used with a view to making recommendations about the development of a full-text, searchable database that would support such usage. The results indicate that levels of usage vary over time, the range of journals covered is small and readers overlook a large proportion of the contents of articles. Furthermore, three reading strategies are observed which indicate that the presentation of journal articles is not ideally suited to their uses. The implications of these findings for developing suitable computer-based applications are discussed.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. (1991) Readers' models of text structures. International Journal of Man-Machine Studies, 35, 913-925. Abstract: Hypertext is often described as a liberating technology, freeing readers and authors from the constraints of "linear" paper document formats. However there is little evidence to support such a claim and theoretical work in the text analysis domain suggests that readers form a mental representation of a paper document's structure that facilitates non-serial reading. The present paper examines this concept empirically for academic articles with a view to making recommendations for the design of a hypertext database. The results show that experienced journal readers do indeed possess such a generic representation and can use this to organise isolated pieces of text into a more meaningful whole.This representation holds for text presented on screens. Implications for hypertext document design are discussed.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. and Morris, M. (1998) From "can they?" to "will they?": extending usability evaluation to address acceptance. AIS Conference Paper, Baltimore, August 1998. Introduction: usability engineering: Within the human-computer interaction (HCI) community, there exists a long and rich research paradigm on "usability engineering (UE)." Within the usability engineering tradition, usability is operationally defined as the effectiveness, efficiency and satisfaction with which specified users can perform particular tasks in a given environment (see e.g., Shackel 1991, Nielsen, 1993). Effectiveness answers: can users perform their tasks? Efficiency means: what resources do users expend to achieve a given outcome (e.g., time, effort)? Finally, satisfaction measures assess how well users like the application. From this perspective, usability is contextually defined in operational terms that designers can see as targets to meet, for example: "Users should be able to perform specified tasks with new tool after W minutes training, with X% effectiveness, at least Y% efficiency, and Z% greater satisfaction than with old interface" where W < infinity, and 0< [X, Y, Z] <100. The strengths of the usability engineering approach include: 1. The use of operationalised measures that are negotiated in context, 2. The direct coupling of usability to tasks the tool must support, 3. The capability of negotiated targets to fit into an iterative design process, and 4. The decoupling of the usability construct from interface features Each of these strengths gives the approach value to the software industry where design practices require targets to be met and where the success of a new tool is determined contextually rather than in any absolute manner. Thus, the usability engineering paradigm has enjoyed a wide range of support from industry. Nonetheless, there are associated weaknesses of this approach. Some of these weaknesses include: 1. Usability criteria are dynamic, not fixed, 2. Usability is thus contextually determined so what works in one context may not work in another and design practices must continually ground themselves in work practices 3. Determining usability criteria requires considerable analytic skill, 4. Generalization beyond context is difficult, 5. Criteria do not determine re-design advice While the approach advocated by usability engineers of deriving appropriate targets for design and testing to meet is useful, it is clear that usability does not fully determine actual system use (see Dillon and Morris 1996). Thus, it is possible that designers may produce a well engineered artifact that meets set criteria, but still fails to gain the acceptance of discretionary users. In other words, usability is a necessary but insufficient determinant of use.

This item is not the definitive copy. Please use the following citation when referencing this material: Dillon, A. and Shaap, D. (1996) Expertise and the perception of structure in discourse. Journal of the American Society for Information Science, 47(10), 786-788. Abstract: Ability to navigate an information space may be influenced by the presence or absence of certain embedded cues that users have learned to recognize. Experimental results are presented which indicate that experienced readers of certain academic journals are more capable than inexperienced readers in locating themselves in an information space in the absence of explicit structural cues.