Principles of Good Interface and Screen Design 241

Step 3: Principles of Good Interface and Screen Design 241

• To match the structure of a paper counterpart. • To make pages more convenient to download. • To make pages more convenient to print. • To simplify page maintenance.

— Generally, restrict to two or three screens of information. — Place critical or important information at the very top so it is always viewable

when the page is opened. • Locate within the top 4 inches of page.

The answer to the question “What should be the maximum length of a Web page?” has no precise answer. Maximum length recommendations in the literature vary, running from “short” to “1 to 2” to “3 to 5” screens, to even more. One serious problem in estab- lishing an exact page size is that the multitudes of Web viewers use a variety of differ- ent browsers and monitors. Another problem is that font types and sizes can vary, impacting how much of a page is visible at any one time. What is viewable on one per- son’s screen, then, may not be entirely visible on another. Another problem is that the viewable depth of a Web screen is somewhat less than the typical business information screen. Very few Web users have screens large enough that enable them to view an entire letter-size page all at once. A business information system, conversely, usually contains standardized applications, consistent-size screens, and standard monitors.

Arguments for shorter pages are that longer pages:

Tax the user’s memory, as related information is more scattered and not always visible.

Can lead to a lost sense of context as navigation buttons and major links disap- pear from view.

Display more content and a broader range of navigation links making it more difficult for users to find and then decide upon what path to follow.

Require excessive page scrolling, which may become cumbersome and inefficient.

Are less conducive to the “chunking” information organization scheme com- monly employed in Web sites.

Arguments for longer pages are that they:

Resemble the familiar structure of paper documents.

Facilitate uninterrupted reading, especially on content pages.

Require less “clicks” for navigating through a Web site.

Are easier to download and print for later reading.

Are easier to maintain because they possess fewer category navigation links to other pages.

Ultimately, page length decisions must be made depending upon the use and goals of the Web site and its pages. In Web page design, what is generally agreed upon is the following:

Minimize page length. Given the scarcity of Web page screen real estate, and its

242 Part 2: The User Interface Design Process

denominator display screen size. To fulfill the “Amount of Information” guide- lines just described will often require a page length to exceed a “screenfull.” Determining an optimum page length will require balancing these factors.

Generally, pages should be long enough to adequately convey the necessary information, but not so long that excessive scrolling becomes a problem. Candidates for short pages are homepages where a site’s identity and goals must

be quickly identified, and navigation pages where all navigation alternatives must be clearly displayed and quickly found. Pages needing to be quickly browsed or read online, and content quickly found should also be short. If pages download slowly and all pages are not always needed, also provide a contents page containing many navigation links to short pages.

Longer pages work best when an entire concept must be understood without interruption. In these cases, present the entire concept in one page with internal links to subtopics. The size of a page may also be governed by the size of a paper or document counterpart. Longer documents will require longer pages. Convenience in downloading or maintaining may also require longer pages. Fewer Web files are easier to maintain. To print all or most of the page content to read offline, use one long page or prepare a version that uses one page.

Restrict a page to two or three screens. This is a very general recommendation that will ultimately be governed by the factors just discussed. Critical or important information at the very top. Critical or important information should be placed where it will be immediately visible when the page is dis- played. In Web page design, this is referred to as “above the fold,” a term bor- rowed from newspaper page layout. Above the fold is about the top 4 inches of a page. “Below the fold” will usually require scrolling to access and may not always be seen.

Web page size will also vary depending upon the user’s task and motivation, the page’s purpose, and the Web page provider’s objectives. If the user is inter- ested and motivated, a longer page may be warranted, reducing the user’s effort in reloading pages. If the user is being “sold” a product, advertising practices should be employed, including keeping pages short. If the page’s purpose is strictly navigation, then one screen is most practical so that all navigation choices are visible. A factor to be determined in establishing page length, then, is the user’s reading “rhythm” (Levine, 1995). A number of the above recommenda- tions are based Koyani et al. (2004).