Web Site Usability, Usefulness, and Visit Frequency

Abstract

A study was conducted to assess the effects of Web site usability on user ratings of site usefulness and site visit frequency. The effects of network connection speed on site usability and usefulness were also assessed. An on-line survey questionnaire was administered to users of Geographical Information System (GIS) Web sites. Usability ratings of five main Web site tasks, a comparative usability rating of the site with other GIS sites, rated usefulness of the site, mean load time of site pages, and other Web site and user data were collected from 51 respondents. A model describing the relationship among variables is described providing quantitative measures of the unique contributions of each variable to usability, usefulness and visit frequency. For the sites in this study, a site's comparative usability and usefulness rating was found to be influenced primarily by how highly the user rated the ease with which information could be found on the site and the reading of textual information. Both comparative usability of the site and site usefulness contributed uniquely to site visit frequency, but were not correlated with each other. Mean load time of Web site page contents, the average time it takes for site to load page contents, did not reliably influence the ease with which site tasks were performed or the comparative usability rating of the site. The utility of a quantitative model describing how variables affect site usage is discussed as are possible reasons for the absence of a reliable effect of mean page load time on site usability and usefulness are also explored.