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Lab 1.7 Exercises

1.7.1. Analyze and Define Structural Design Issues

Information structures are often combinations of the four fundamental structures. For example, a node within a hierarchical structure might actually be an embedded Web structure.

a) Define a circumstance where this might be the most appropriate structural design.

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“Information overload” is human-computer interface (HCI) issue of concern to hypertext document designers. An example of information overload previously given dealt with hierarchical structures that are “too shallow.”

A1:

Answer: It is quite common for a hierarchically designed Web site to have links on the “root page” that extend to the Internet “in general.” In such a case, the “Internet/Web” is logically one of the nodes of the hierarchical structure. For example, in the following diagram, Figure 1.17, the “cyberspace” node is the entire World Wide Web.

Figure 1.17. A “Composite” Information Structure


b) What is the potential impact of short-term memory on information overload?

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A2:

Answer: Short-term memory considerations would suggest that hierarchical structures have a maximum of 9 ( i.e., 7 + 2) nodes at the first level (that level immediately below the root node). If the number of nodes at that level is greater than 9, a user would have difficulty retaining them in short-term memory (information overload) and the hierarchy would be considered “too shallow.”

c) Discuss the advantages and disadvantages of a hierarchical structure versus a Web structure. (Note: Consider the problem of porting existing documents to Web pages.)

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A3:

Answer: If sets of pages can be easily grouped into their own Web “documents” with little or no relationship to other groups, there is little need to have many links between them. This tends to lead away from a Web structure. In addition, the more the topics themselves are hierarchical (e.g., a company organization), the more you should tend toward a hierarchical structure.

Web-based structures are more suited to information fragments with a lot of interrelationships. On the other hand, if not properly managed, Web structures can get out of hand and may be difficult to navigate.

When porting from paper-based documents to a Web document, a hierarchical structure is quicker to implement as the document is probably already in some kind of hierarchy (chapters, sections, and so forth).

d) The size of a “chunk” of information is important to retaining it. Compare the amount of information in each article on the CNN Web site (www.cnn.com) and Time Magazine Web site (http://www.time.com/time/magazine/toc/).

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A4:

Answer: Basically all of the articles on the CNN Web site are single pages that provide you with just the basic details of a particular story. There are links to other stories (others about a single incident or about related topics), but each article is short and can be typically read in a few minutes. It is therefore easier to remember most of the article.

On the other hand, the Time Magazine has magazine-length articles (what else?). These are spread across multiple pages and each page usually has more text than a page on the CNN site. Because more information is presented, a smaller percentage of that information is retained.


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