As the number of Web users and the diversity of Web applications continues to explode, Web Quality of Service (QoS) is an increasingly critical issue in the domain of e-Commerce [re]. This paper presents experiments designed to estimate users' tolerance of QoS in the context of e-commerce. In addition to objective measures we discuss contextual factors that influence these thresholds and show how users' conceptual models of Web tasks affect their expectations. We then show how user thresholds of tolerance can be taken into account when designing web servers. This integration of user requirements for QoS into systems design is ultimately of benefit to all stakeholders in the design of Internet services.

... makes Quality of Service (QoS) increasingly critical [15]. To date, the majority of research on QoS is systems oriented, focusing on traffic analysis, scheduling, and routing. Relatively minor attention has been paid to user-level QoS issues. It is not yet known how objective system quality relates to users' subjective perceptions of quality. This paper presents the results of quantitative experiments that establish a mapping between objective and perceived QoS in the context of Internet commerce. We also conducted focus groups to determine how contextual factors influence users' perceptions of QoS. We show that, while users' perceptions of World Wide Web QoS are influenced by a number of contextual factors, it is possible to correlate objective measures of QoS with subjective judgements made by users, and therefore influence system design. We argue that only by integrating users' requirements for QoS into system design can the utility of the future Internet be maximized.

Web search services are now a major source of information for a growing number of people. We need to know more about how users search Web search engines to improve the effectiveness of their information retrieval. This paper reports results from a major study exploring users ’ information searching behavior on the EXCITE Web search engine. The study is the first to investigate Web users ’ successive searching behavior as they conduct related searches over time on the same or evolving topic. A total of 316 EXCITE users responded to an interactive survey accessed through EXCITE’s homepage. Users provided information on their search topics, intended query terms, search frequency for information on their topic, and demographic data. Results show that when searching the Web: users tend to employ simple search strategies; and often conduct more than one search (successive searches) over time to find information related to a particular topic. Implications for the design of Web search services are discussed.

Shared networks are now able to support a wide range of applications, including real-time multimedia. This has led the networking community to consider a wider range of network Quality of Service (QoS) guarantees and pricing schemes. To date, the QoS required by networked multimedia applications has been described in terms of technical parameters. We argue that, in order to maximize the realized quality of any network, the QoS requirements of networked multimedia applications should be based on the value that users ascribe to the media quality they receive in the context of a particular task. This argument is supported with results from a set of studies in which users' perceptions of media quality was investigated for a listening task. We found that users' expectancies of quality directly influenced their ratings: low expectancies produce higher ratings for the same level of objective quality - provided that quality is predictable. In conclusion, we outline the implications of our stud...

Abstract-To accommodate applications with highly variable degrees and categories of Quality of Service (QoS) requirements, a major effort has been invested to overcome the traditional best-effort service quality of the Internet [1],[2]. Nevertheless, there has been a shift towards weak QoSassurance paradigms based on the differentiation of different QoS levels [3]. What is currently missing is a technique for specifying user preferences for QoS and network charging mechanisms. If the Internet is to remain economically viable, demand for Internet services must be maintained. Specifying users ' QoS requirements therefore has potentially crucial implications for providing a degree of service that will encourage users to pay for the quality that they receive. This paper investigates the role of conceptual design in establishing users ' mental representations of Internet services and their charges. We report empirical work that shows how these models can be used to predict the acceptability of Internet services. Preliminary guidelines for the design of QoS charging mechanisms are presented. I.