Develop System Menus and Navigation Schemes 347

Step 4: Develop System Menus and Navigation Schemes 347

Hierarchy of generality or importance. Having identified the information units, information is now organized in according to importance or generality, from gen- eral to specific. A hierarchical tree is the most recommended organization scheme; Sun Microsystems (1998) suggests that whenever possible

State conclusions and link to supporting details.

Enumerate categories of information and link them to detailed listings.

Summarize information and link to full-length treatments.

A document organizational tree structure, (table of contents, chapters, sec- tions, and subsections) is a good scheme, because people are very familiar with, and have an excellent mental model of this organization. Such a structure pro- vides information about information sequence, information quantity, and the relationships existing between components. Other organizational schemes include topics followed by subtopics, or prioritization from most to least impor- tant. The objective is to allow the user to scan the page and then select relevant and useful content for further review. Excessive fragmentation of a long, sequen- tial story, however, should be avoided. Reading will be impeded and printing made more difficult.

Structure the relationships. Identify the relationships that exist between various elements in the hierarchical tree. In a large Web site, two levels of navigation will exist. The first is movement within the subject area. This navigation includes moving within a branch—up to a parent page or down to a child page. It also involves navigating across branches to sibling pages or other sections of a site. What points on other tree branches it will be beneficial to go directly to then, must also be established. The second navigation type is global or site-wide. What other site features, such as search a facility, site maps, and other major content areas should be mentioned on each page? Do not mention all features on all pages. Restrict the number presented to the several most useful features.

To unveil the Web site’s structure, use progressive disclosure. Heading levels, shown in varying type sizes (as on paper), will also be helpful in aiding under- standing of site organization.

Hierarchical tree. Web site pages should be organized as offshoots of a single home- page. If a site has a large number of information categories, and each category contains a lot of content, create submenus to aid navigation. The design goal: a well-balanced hierarchical tree that facilitates quick access to all information and also helps people understand how the site is organized. The so-called spoke design, where every page is linked to every other page, has been found to lead to lower usability.

Hierarchical breadth has been found by many research studies to be greatly preferable to hierarchy depth. A few menus with a larger number of choices are better than a large number of menus each with a smaller amount of choices. When menu levels go to four, five, or more, the chance of users becoming lost or disoriented is greatly increased. As studies have found (Zaphiris and Mtei, 1998; Larson and Czerwinski, 1998), restrict, whenever possible, the hierarchical tree to two levels requiring no more than two clicks to reach the deepest content. A two-

348 Part 2: The User Interface Design Process