Subject directories and search engines

What if you don't know what information is out there, or where it is located? In general, there have been two different approaches to searching for information on the World Wide Web - subject directories and search engines. However, like everything else in the online universe, the clear-cut division between subject directories and search engines is changing. Many newer searching tools include both.

Keywords are used with both approaches, but in somewhat different ways. Subject directories are specialized websites that select other sites and organize them under broad subject headings; no two directories categorize their materials in the same way, and each directory covers only a small subset of the entire Internet. To use subject directories most effectively, choose broad, inclusive keywords because unique terms will often yield no results. Keep in mind, however, that failure to find information does not mean it does not exist. The directory simply may not have picked it up for indexing.

Search engines, on the other hand, are software programs that consist of comprehensive indexes of the Internet. One of the most popular of these, Google, is rapidly becoming a verb as well (as in, "google it"). However, there are many others. You can find a catalog of them, listed by category, at <>. Their (nearly impossible) goal is to index every word of every Web page in their databases, but even the biggest search engines index only 60-80% of the Web (Gould, 1998). Search engine databases are created by computer programs - variously called robots, spiders, webcrawlers, or worms -that work constantly to collect and index Web pages.

When you provide keywords to a search engine, it will attempt to honor your request with a ranked list ("hit" list) of sites. However, because so much information is available, it is common to get overloaded with results that mix trivial or irrelevant results with the pertinent ones. Search engines attempt to help with this problem by applying ranking algorithms or formulas that determine the order in which the results are displayed. Small differences in these algorithms have a major effect on the results obtained, even when you use identical search terms. Thus, it is a good idea to use multiple search engines, rather than relying on the results from only one.

To use search engines effectively, choose very specific keywords and combine them in an appropriate syntax to take advantage of advanced search features.

The more uncommon the word or phrase, the more manageable the number of retrievals will be, and the fewer irrelevant documents that will appear.

Tapping other informal and formal communication channels

There are many ways to tap into the vast stream of scientific information that exists in the world. Some are informal and unmediated; others are formal, with explicit rules that restrict the kind or quality of information that is admitted into their system.

If literature searching were courtship, informal channels would be face-to-face dates, but formal channels would be blind dates arranged by friends. To carry the analogy further, the serious suitor eager for the best match should try every appropriate avenue (Cooper, 1998).

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