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Structure. Part three of a four-part series.

by Geoff Hart

Previously published as: Hart, G.J. 2002. Structure paves the way online (part three of four). http://www.techwr-l.com/techwhirl/magazine/usersadvocate/usersadvocate_structure.html

Click here to read part 1 of this series.

Click here to read part 2 of this series.

What I’ve called structure in the first article in this series has various other names, the most familiar of which are probably “hierarchy” or “information architecture”. Whichever word you use, structure encapsulates the relationships between the components of a site that visitors will use to navigate to the information they seek. Structure is simple enough to define, but can be devilishly tricky to create. A succesful site structure must create what psychologists refer to as a schema: a mental model that visitors can use to understand where you’ve hidden the content I discussed in the previous column.

To create successful structures, you must understand your audience well enough to know what kinds of schemata they will benefit from. The ideal schema is so familiar that visitors can use it unconsciously—that is, without having to think much about the schema so they can instead think about what they’re seeking. Most structures fall into one of four broad categories: ordered (alphabetical or numerical), functional, hierarchical, and web.

Ordered structures rely on our knowledge of the order inherent in a body of information to guide where we look. Alphabetical structures are the most familiar, and use the well-known order of the English alphabet to arrange any information that can be defined by its position within the alphabet; dictionaries and encyclopedias are obvious examples of this structure. Numerical structures are equally familiar, but rely on the equally well-known sequence followed by numbers; products grouped by price and historical data arranged in a timeline are obvious examples. Many other “orders” exist, including physical (e.g., geographical maps, a blueprint of a house), logical (e.g., you can’t print your document until you’ve turned on the printer, cause and effect), and organizational (e.g., the well-defined ranks in a military organisation).

Functional structures rely on the human ability to group things based on similarities in their function (purpose). One familiar example might be the Web site of a company that sells several products, and devotes a separate part of the site to each category of product. Companies that sell computer-related materials on the Web, for example, typically divide their site into at least three different functional groupings: hardware, consumables for that hardware (e.g., ink, paper), and software. An equally logical functional structure might be to gather all the products for printers (the printers, paper and ribbons, and printing software) in one area and gather storage products (disk drives, diskettes, and disk utiliity software) in another. Which approach makes the most sense depends on how your audience will approach the site.

Hierarchical structures depend on our ability to subdivide broad groups into narrower categories, each of which can in turn be subdivided into other categories. The more subdividing we do, the more similar the items grouped under these categories become. The dichotomous keys that biologists use to identify organisms are one good example: Is this organism an animal, or a plant? Now that we know it’s a plant, is it a flowering plant or not? And so on. The further down the hierarchy you go, the more choices you exclude and the fewer that remain for you to choose among. Organization charts represent another good example of a hierarchical structure. Although they could also be considered ordered structures, hierarchies differ in that their order can be arbitrary and based on degrees of similarity rather than on a universally acknowledged sequence; for example, technical communicators fall under the product development department in some companies, under Sales and Marketing in others, and stand as their own department in a third group of companies.

Web structures are the source of the name for the World Wide Web itself: they are as highly interconnected as the parts of a spider’s web, with a bewildering variety of links between related topics. In web structures, as in the Web itself, paths potentially exist between any two related topics, and you can often reach seemingly distant parts of a body of information by following a surprisingly short chain of links. This may be familiar to you in the form of the party game “seven degrees of separation”, in which the goal is to establish a chain of relationships between yourself and someone famous (“Kevin Bacon” in one popular version of the game). The problem with such structures is that their unparalleled flexibility comes at the cost of unpredictability: nobody knows all possible paths, and even the best path to a specific piece of information may be inobvious.

In practice, effective sites judiciously combine aspects of all four structures, with the most appropriate structure chosen for each component of the site. Moreover, you can provide access to any given portion of a site in more than one way; for example, if you’re selling ink for inkjet printers, there’s no reason you couldn’t link to it under printers (hierarchically), under consumables (functionally), under ink (alphabetically), and under price (numerically). One of the challenges in working with audiences is that what seems to be a logical structure to you may be completely foreign to someone else, and vice versa. One of the advantages of online information is that you don’t have to restrict yourself to only one of these approaches.

Once you’ve developed a variety of structures to support access to information, you must then link these structures together. Again, familiarity to the user is important, because visitors want to concentrate on what they’re seeking, not how they’re seeking it. Time-tested schemata such as a table of contents and index do the job nicely. The table of contents (i.e., a site map) provides a high-level view of the structures that exist on your site, whereas an index provides a low-level view of individual topics for those who aren’t interested in the big picture. To complete the picture where neither a table of contents nor an index is what the visitor needs, provide simple navigational clues that communicate the structure to the visitor: these include summaries (“this part of the site contains the following information”), cross-references (“see also: consumables”), and other useful tools (e.g., color pickers for a clothing merchant, ISBN lookups for a book seller).

Click here to read part 4 of this series.

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