语言教学 | 普渡大学写作教学系列Research&Citation9-Searching Online(2)

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4、Searching with a Search Engine

A search engine is a device that sends out inquiries to sites on the Web and catalogs any Web site it encounters, without evaluating it. Methods of inquiry differ from search engine to search engine, so the results reported by each one will also differ. Search engines maintain an incredibly large number of sites in their archives, so you must limit your search terms in order to avoid becoming overwhelmed by an unmanageable number of responses.

Search engines are good for finding sources for well-defined topics. Typing in a general term such as "education" or "Shakespeare" will bring back far too many results, but by narrowing your topic, you can get the kind (and amount) of information that you need.

Example:

• Go to Google (a search engine)

• Type in a general term ("education")

• Add modifiers to further define and narrow your topic ("rural education Indiana")

• Be as specific as you can ("rural education Indiana elementary school")

• Submit your search.

Adjust your search based upon the number of responses you receive (if you get too few responses, submit a more general search; if you get too many, add more modifiers).

Learn how the search engine works

Read the instructions and FAQs located on the search engine to learn how that particular site works. Each search engine is slightly different, and a few minutes learning how to use the site properly will save you large amounts of time and prevent useless searching.

Each search engine has different advantages. Google is one of the largest search engines, followed closely by MSN and Yahoo . This means that these three search engines will search a larger portion of the Internet than other search engines. Lycos allows you to search by region, language, and date. Ask allows you to phrase your search terms in the form of a question. It is wise to search through multiple search engines to find the most available information.

Select your terms carefully

Using inexact terms or terms that are too general will cause you problems. If your terms are too broad or general, the search engine may not process them. Search engines are programmed with various lists of words the designers determined to be so general that a search would turn up hundreds of thousands of references. Check the search engine to see if it has a list of such stopwords. One stopword, for example, is "computers." Some search engines allow you to search stopwords with a specific code (for Google, entering a "+" before the word allows you to search for it).

If your early searches turn up too many references, try searching some relevant ones to find more specific or exact terms. You can start combining these specific terms with NOT (see the section on Boolean operators below) when you see which terms come up in references that are not relevant to your topic. In other words, keep refining your search as you learn more about the terms.

You can also try to make your terms more precise by checking the online catalog of a library. For example, check THOR+, the Purdue University Library online catalog, and try their subject word search. Or try searching the term in the online databases in the library.

Most search engines now have "Advanced Search" features. These features allow you to use Boolean operators (below) as well as specify other details like date, language, or file type.

Know Boolean operators

Most search engines allow you to combine terms with words (referred to as Boolean operators) such as "and," "or," or "not." Knowing how to use these terms is very important for a successful search. Most search engines will allow you to apply the Boolean operators in an "advanced search" option.

AND

AND is the most useful and most important term. It tells the search engine to find your first word AND your second word or term. AND can, however, cause problems, especially when you use it with phrases or two terms that are each broad in themselves or likely to appear together in other contexts.

For example, if you'd like information about the basketball team Chicago Bulls and type in "Chicago AND Bulls," you will get references to Chicago and to bulls. Since Chicago is the center of a large meat packing industry, many of the references will be about this since it is likely that "Chicago" and "bull" will appear in many of the references relating to the meat-packing industry.

OR

Use OR when a key term may appear in two different ways.

For example, if you want information on sudden infant death syndrome, try "sudden infant death syndrome OR SIDS."

OR is not always a helpful term because you may find too many combinations with OR. For example, if you want information on the American economy and you type in "American OR economy," you will get thousands of references to documents containing the word "American" and thousands of unrelated ones with the word "economy."

NEAR

NEAR is a term that can only be used on some search engines, and it can be very useful. It tells the search engine to find documents with both words but only when they appear near each other, usually within a few words.

For example, suppose you were looking for information on mobile homes, almost every site has a notice to "click here to return to the home page." Since "home" appears on so many sites, the search engine will report references to sites with the word "mobile" and "click here to return to the home page" since both terms appear on the page. Using NEAR would eliminate that problem.

NOT

NOT tells the search engine to find a reference that contains one term but not the other. This is useful when a term refers to multiple concepts.

For example, if you are working on an informative paper on eagles, you may encounter a host of Web sites that discuss the football team the Philadelphia Eagles, instead. To omit the football team from your search results, you could search for "eagles NOT Philadelphia."

5、Searching with a Web Directory

There are two main types of directories: those that are hierarchical (i.e. that lead one from a general topic to a more specific one) and those that list sources in some sort of order (most commonly alphabetical). The first type of index often contains a broad range of topics while the second usually contains sources designed to address a particular topic or concern.

Most search engines have some sort of index attached to them. More prominent and well-developed ones include The Open Directory Project , Yahoo!, and Google . Indexes are valuable for Web researchers who have an area on which they want to focus, but do not yet have a specific topic. An index can help a writer get general information or a "feel" for the topic.

An Example:

• Go to Yahoo! (contains a Web directory)

• Find a topic that interests you ("education")

• Follow it through specifics ("rural education", "Rural Education Institute")

• "Rural Education Institute" is a specific topic that can be feasibly researched, either by following the listed links or by using that phrase in a keyword search.

6、Search Engine and Web Directory List

The following is a list of some of the most powerful search and metasearch engines and most comprehensive web directories.

• All4one: One of the first metasearch engines, All4One allows simultaneous searching of 10 major search engines.

• Bing: Microsoft's search engine.

• Dogpile: A metasearch engine that will search Google, MSN, Yahoo, and Ask.

• Environment Web Directory: A web directory that focuses on environmental and health issues.

• Excite: A search engine that lets you search by language, for video, audio, and mp3, and by relevant date.

• Google: Includes a new type of search, "Google Scholar," which allows you to search for more academically-oriented searches.

• Lycos: A search engine that allows for news searches but does not have many advanced search features.

• Metacrawler: A metasearch engine and will search other search engines.

• The Open Directory Project: One of the largest and most comprehensive human-edited directories in the world. Only higher quality websites will be listed here as each site submitted must be approved by a directory editor.

• WebCrawler: Another search engine that allows searching by location, domain name, and for multimedia.

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