Understanding the relation between network quality of service and the usability of distributed multimedia documents

Network quality of service, as manifest in the delays users experience, effects both user perceptions and performance. Unfortunately, existing research on the usability of network-based documents and applications does not always adequately address the issue of network delays. In this article, we assert that researchers must document, and should consider manipulating, the delays users experience during studies exploring the usability of network-based computing systems. This article provides an overview of the factors that contribute to the delays users experience and the issues involved in modeling these delays. It also provides advice on how delays should be documented and discusses the advantages and disadvantages of the various techniques available for integrating delays into usability studies and controlled experiments. The existing literature reports numerous inconsistent results, which may be due to different experimental designs, participants, tasks, independent variables, and dependent variables. Therefore, this article concludes by outlining the experimental design considerations that must be considered as the relation between network quality of service and the usability of network-based computing systems is investigated. The result is a framework that will guide future research and allow more effective comparisons of the results of that research.