A usability assessment of online indexing structures in the networked environment

Usability of Web sites has become an increasingly important area of research as Web sites proliferate and problems with use are noted. Generally, aspects of Web sites that have been investigated focus on such areas as overall design and navigation. The exploratory study reported on here investigates one specific component of a Web site—the index structure. By employing index usability metrics developed by Liddy and Jörgensen (1993; Jörgensen & Liddy, 1996) and modified to accommodate a hypertext environment, the study compared the effectiveness and efficiency of 20 subjects who used one existing index (the A–Z index on the FedStats Web site at http://www.fedstats.gov) and three experimental variants to complete five researcher-generated tasks. User satisfaction with the indexes was also evaluated. The findings indicate that a hypertext index with multiple access points for each concept, all linked to the same resource, led to greater effectiveness and efficiency of retrieval on almost all measures. Satisfaction measures were more variable. The study offers insight into potential improvements in the design of Web-based indexes and provides preliminary assessment of the validity of the measures employed.