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Insights from Human Factors International
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In This Issue:
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Linking and Searching
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Bob Bailey, Ph.D., Chief Scientist for HFI, gives observations and guidelines
on the effective use of searching and linking.
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The Pragmatic Ergonomist
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Dr. Eric Schaffer, Ph.D., CPE, founder and CEO of HFI offers practical
advice.
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Introduction
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Sanjay Koyani at the National Cancer Institute and I did a quick survey
of the available literature on linking and searching.
We organized our findings into a series of observations and guidelines
that may be helpful to designers dealing with similar issues.
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Major Observations
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Preference for using links versus searching appears to depend on the
Web site and the tasks being performed (Spool and Ojakaar, 2001).
When looking for something specific or unique, users prefer to use the
search function (Spool, 2002).
Linking tends to be more effective than searching to find content (Ojakaar
and Spool, 2001).
Linking through to a target may require fewer clicks than searching (Spool,
2002).
Linking usually results in users exploring more related content (Spool,
Schroeder and Ojakaar, 2001a).
Users become less successful with each search attempt (Nielsen, 2001;
Spool, Schroeder and Ojakaar, 2001b; Spool and Schroeder, 2001):
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Successful Searches |
| Search Attempts |
Nielsen |
Spool, et.al. |
| First |
51% |
55% |
| Second |
32% |
38% |
| Third |
18% |
0% |
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About half of unsuccessful searches were the result of users making input
errors, which included misspellings, using inappropriate case, spaces
and punctuation, misusing plurals, and typing mistakes (Spool, 2002).
Designers and users do not tend to use the same descriptive words. Furnas,
et.al. (1984) reported that agreement depended on how the terms were initially
determined:
- Without conducting any studies: Up to 20% agreement,
- By conducting a survey of potential users: 20% to 40% agreement, and
- By conducting a survey and allowing up to five synonyms for each term:
40% to 60% agreement.
Advanced search features do not seem to help users. A couple of studies
(Nielsen, 2001; Spink, et.al., 1999) have shown that most users tended
to employ very simple search strategies, usually by entering one or two
words into the search box.
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Guidelines
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Include both links and a search capability on all key pages of a Web
site. Users do not seem to be predisposed to using either linking or searching
behaviors; the behavior used appears to depend primarily on the site's
content and associated tasks.
When attempting to find information or a product that is not specific
and unique, linking is used more frequently and tends to be more successful
than searching. Linking requires less effort from users, and frequently
allows them to find desired content faster. Also, linking allows users
to view substantially more related site content. A good way to help encourage
more linking is to provide more links on pages.
For specific, unique items, like a book or CD title, encourage users
to use the search capability. This might be best accomplished by how prominently
the search capability is positioned throughout the site.
When searching is used:
- Make every effort to ensure that users get relevant results on their
first search attempt,
- Be aware of, and make provision for, the terms (keywords) that users
typically will use for searching,
- Provide search templates (collections of pre-selected keywords) to
help users better formulate their search queries,
- Accommodate misspellings, the use of inappropriate case, spaces and
punctuation, misused plurals, and typing errors, and
- Do not rely on advanced search features to improve the effectiveness
of a search capability.
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References
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Furnas, G., Landauer, T., Gomez, L. and Dumais, S. (1984), Statistical
semantics: Analysis of the potential performance of keyword information
systems, in Human Factors in Computer Systems,
Edited by John Thomas and Michael Schneider, 187-242.
Nielsen, J. (2001), Search:
Visible and simple, Alertbox, May 13.
Ojakaar, E. and Spool, J.M. (2001), Getting them to what they want, User
Interface Engineering Report.
Spink, A., Bateman, J. and Jansen, B.J. (1999), Searching the Web: A
survey of Excite users, Internet Research: Electronic Networking Applications
and Policy, 9(2), 117-128.
Spool, J. (2002), In search of the perfect search: Building the perfect
on-site search, CHI 2002 Tutorial.
Spool, J., Schroeder, W. and Ojakaar, E. (2001), Users
continue after category links, User Interface
Engineering Newsletter, December 4.
Spool, J. and Schroeder, W. (2001), People
search once, maybe twice, User Interface Engineering
Newsletter, November 20.
Spool, J. and Ojakaar, E. (2001), Are
there users who always search? User Interface
Engineering Newsletter, May 13.
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So there are some tasks that lead you to make search the primary method
of navigation. For example, in book-selling sites, over 80% of users know
the title or author. It is easy to put this into search. But in most cases
search is a backup. For most sites, frequent use of search is an indication
of a broken navigational structure. If the user does not know exactly
what they want, search is often time consuming and painful.
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Past Issues
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