ABSTRACT
Usability is the most fundamental attribute that determines the ease with which users interact with a product. There have been numerous demonstrations of the value of incorporating usability into the design lifecycle for products in general and for Web applications in particular (see Bias and Mayhew 2005; Richeson et al., this volume). Bevan (2005) showed that the bene£ts of user-centered design include reduced development costs, increased sales on e-commerce Web sites, and increased employee productivity, ef£ciency, and retention. Because Web usability is an area within the general domain of computer software usability, many issues relevant to software usability also apply to Web usability (Nielsen 2000; Vu and Proctor 2006). Usability for Web design is typically de£ned to include the following factors (e.g., Brink, Gergle, and Wood 2002; Coutaz and Calvary 2008; Lazar 2006):
Evaluations of Web usability can be guided by and based on the aforementioned attributes. Tullis and Albert (2008) provide an overview of user performance metrics that can be used in evaluating Web usability. As emphasized by many books, articles, and online columns dedicated to Web usability (for examples, see Appendix A), the purpose, target audience, and core user tasks of a Web site must be considered and identi£ed when evaluating Web usability.
