Characterizing Browsing Strategies in the World-Wide Web

Abstract


This paper presents the results of a study conducted at Georgia Institute of Technology that captured client-side user events of NCSA's XMosaic. Actual user behavior, as determined from client-side log file analysis, supplemented our understanding of user navigation strategies as well as provided real interface usage data. Log file analysis also yielded design and usability suggestions for WWW pages, sites and browsers. The methodology of the study and findings are discussed along with future research directions.
Keywords


Hypertext Navigation, Log Files, User Modeling
Introduction


With the prolific growth of the World-Wide Web (WWW) [Berners-Lee et.al, 1992] in the past year there has been an increased demand for an understanding of the WWW audience. Several studies exist that determine demographics and some behavioral characteristics of WWW users via self-selection [Pitkow and Recker 1994a & 1994b]. Though highly informative, such studies only provide high level trends in Web use (e.g. frequency of Web browser usage to access research reports, weather information, etc). Other areas of audience analysis, such as navigation strategies and interface usage remain unstudied. Thus, the surveys provide estimations of who is using the WWW, but fail to provide detailed information on exactly how the Web is being used. Actual user behavior, as determined from client-side log file analysis, can supplement the understanding of Web users with more concrete data. Log file analysis also yields design and usability guidelines for WWW pages, sites and browsers.
This paper presents the results of a three week study conducted at Georgia Institute of Technology that captured client-side user events of NCSA's XMosaic. Specifically, the paper will first present a review of related hypertext browsing and searching literature and how it's related to the Web, followed by a description of the study's methodology. An analysis of user navigation patterns ensues. Lastly, a discussion and recommendations for document design are presented.

Literature Review


Many studies have addressed user strategies and usability of closed hypermedia systems, databases and library information systems [Caramel et. al., 1992]. Most distinguish between browsing and searching. Cove and Walsh [Cove et. al. 1988] include a third browsing strategy:
Search browsing; directed search; where the goal is known
General purpose browsing; consulting sources that have a high likelihood of items of interest
Serendipitous browsing; purely random
This continuum provides a nice middle ground to distinguish between browsing as a method of completing a task and open ended browsing with no particular goal in mind. Marchionini [Marchionini, 1989] further develops this distinction in designating open and closed tasks. Closed tasks have a specific answer and often integrate subgoals. Open tasks are much more subject oriented and less specific. Browsing can be used as a method of fulfilling either open or closed tasks.
Intuitively, it would seem that browsing and searching are not mutually exclusive activities. In Bates's [Bates, 1989] work on berrypicking, a user's search strategy is constantly evolving through browsing. Users often move back and forth between strategies. Similarly, Bieber and Wan [Bieber & Wan, 1994] discuss the use of backtracking within a multi-windowed hypertext environment. They introduce the concept of "task-based backtracking," in which a user backtracks to compare information from different sources for the same task or to operate two tasks simultaneously. A similar technique, in a Web environment, would be backtracking to review previously retrieved pages.

All of these studies were performed on closed, single-author systems. The WWW however, is an open, collaborative and exceedingly dynamic hypermedia system. These previous findings provide the basis and structure for the describing the ways a user population behaves in a dynamic information ecology, like the WWW.

Given that we expect to find the same kinds of strategies used in the WWW, supporting both the browser and the searcher in designing WWW pages and servers is necessary, although difficult. Furthermore, supporting the kind of task switching described by Bates and Beiber and Wan adds another level of complexity because the work implies that a user should be able to switch strategies at any time.

It has long been recognized that methods for supporting directed searching are needed. As a response to this, certain WWW servers are completely searchable and there are World-Wide Web search engines available.

Supporting browsing, though, may be a more difficult task. Both Laurel [Laurel, 1991] and Bernstein approach the topic of how to assess and design hypertexts for the browsing user. Laurel considers interactivity to be the primary goal. She defines a continuum for interactivity along three variables: frequency (frequency of choices), range (number of possible choices) and significance (implication of choices). Laurel contends that users will pay the price "often enthusiastically -- in order to gain a kind of lifelikeness, including the possibility of surprise and delight." Bernstein takes a slightly different approach with his "volatile hypertexts" [Bernstein, 1991]. He argues that the value of hypertext lies in its ability to create serendipitous connections between unexpected ideas.

There is a tension between designing for a browser and designing for a searcher. The logical hierarchy of a file structure or a searchable database may work fine for a closed-task, goal oriented user. But a user looking for the unexpected element or a serendipitous connection may be frustrated by the precision required by these methods. The first step in balancing this problem is to determine what strategies are being used by the population. In order to do this, we collected log files of users interacting with the Web.