Searching the Web

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Searching the Web
Tutorial 3

• Using Search Engines and
• Directories Effectively

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Types of Search Questions

• Specific question
• easy to phrase
• easy to recognize the answer when you find it.
• Exploratory question
• open-ended question
• may be harder to phrase
• may be hard to determine when you find a good
  answer.

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Specific Question
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Exploratory Question
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Web Search Process
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Web Search Strategy

• You may need to reformulate, or more clearly
  state your question.
• Synonyms for terms.
• Find unique phrases to target your topic or
  question.

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Using Search Engines

• Four Broad Categories Of Search Tools
• Search engines
• Directories
• Metasearch engines
• Other Web resources such as Web bibliographies

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Understanding Search Engines

• Search engine a Web site (or part of a Web site)
  that finds other Web pages that match a word or
  phrase you enter.
• Search expression or query the word or phrase
  you enter in a search engine.
• May also include instructions that tell the
  search engine how to search.
• A search engine does NOT search the Web to find a
  match it searches only its own database of
  information about Web pages that it has
  collected, indexed, and stored.

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Understanding Search Engines

• Hit a Web page indexed in the search engines
  database that contains text that matches your
  search expression.
• Most search engines report the number of hits
  they find.
• Results pages a list of Web pages in a search
  engine that contain hyperlinks to the Web pages
  that contain text that matches your search
  expression.

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Understanding Search Engines

• Web robot (bot or spider) a program that
  automatically searches the Web to find new Web
  sites and update information about old Web sites
  that already are in the database.
• Most search engines allow Web page creators to
  submit the URLs of their pages to search engine
  databases.
• Search engine operators often sell advertising
  space on the search engine Web page and on the
  results pages.

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Understanding Search Engines

• Sponsored links paid placement links on results
  pages.
• Banner ad a sponsored link that appears in a box
  on the page (usually at the top, but sometimes
  along the side or bottom of the page).
• Revenue from sponsored links and banner ads is
  used to generate profit after covering the costs
  of maintaining the computer hardware and software
  required to search the Web and to create and
  search the database.

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Understanding Search Engines

• See Figure 3.6, p. WEB 161

Google search results for the search term car
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Using More Than One Search Engine

• Each search engine
• includes different Web pages in its database.
• uses different rules to evaluate search
  expressions.
• Best way to determine how a specific search
  engine interprets search expressions
• read the Help pages on the search engine Web
  site.
• Search engines change the way they interpret
  search expressions from time to time
• read the Help pages regularly.

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Understanding Search Engine Databases

• Each search engine
• database stores different collections of
  information about the pages that exist on the Web
  at any given time.
• database indexes the information it has collected
  from the Web differently.
• robots collects information from a Web pages
  title, description, keywords, HTML tags, or a
  certain number of words from each Web page.

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Understanding Search Engine Databases

• Current Developments in
  Electronic Commerce
• and reports about electronic commerce
  developments."
• commerce, electronic data interchange, value
  added reseller, EDI, VAR, secure socket layer,
  business on the internet"

• Meta tag HTML code that a Web page creator
  places in the page header for the specific
  purpose of informing Web robots about the content
  of the page.

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Understanding Search Engine Databases

• Full text indexing search engine stores entire
  content of every Web page indexed.
• Stop words common words, such as and, the, it,
  and by, that many search engines omit from their
  databases.
• Many search engines include information about
  their search engines, robots, and databases on
  their Help or About pages.

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Search Engine Features

• Page ranking a way of grading Web pages by the
  number of other Web pages that link to them.
• URLs of Web pages with high rankings are
  presented first on search results pages.
• Natural language query interface users can enter
  a question exactly as they would ask a real
  person.
• Parsing the procedure of converting a natural
  language question into a search expression.
• Stemming the use of the root form of a word to
  find results containing the root word and its
  variations, which are created by adding standard
  endings to the root word.

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Search Engine Features

• See Figure 3-9, p. WEB 166

Natural language query on Ask.com
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Using Directories and HybridSearch Engine
Directories

• Web directory a listing of hyperlinks to Web
  pages that is organized into hierarchical
  categories.
• Difference between a search engine and a Web
  directory
• people select the Web pages to include in a Web
  directory.
• Many directories allow a Web page to be indexed
  in several different categories.
• Weakness of a Web directory
• Must know which category is likely to yield what
  info. you seek.
• Yahoo! is one of the oldest and most respected
  directories on the Web.

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Using Directories and HybridSearch Engine
Directories

• See Figure 3-10, p. WEB 168

Yahoo! Web directory
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Using Directories and HybridSearch Engine
Directories

• Hybrid search engine directory combination of
  search engine and directory.
• Can help identify which category is likely to
  contain the information you need.
• After you enter category, search engine is useful
  for narrowing search even further.
• Enter search expression to limit search to that
  category.

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Using Metasearch Engines

• Metasearch engine
• search several engines at same time
• does not have its own database of Web information
• accepts a search expression and transmits it to
  several search engines
• each run the search expression against their
  databases
• each returns results to the metasearch engine
• metasearch engine reports consolidated results
  from all search engines it queried
• Mamma.com was one of the first metasearch
  engines on the Web.

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Using Metasearch Engines

• See Figure 3-14, p. WEB 174

Mamma.com was one of the first metasearch
engines on the Web.
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Using Metasearch Engines

• In the Kartoo metasearch engine, hits are shown
  as images each image is clustered around words
  that appear in the results pages.
• When the pointer is moved over a word, the links
  appear as lines between the word and the images.
• To refine a search, click a word to add it to the
  search expression.
• See Figure 3-14, p. WEB 174

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Using Other Web Resources

• Web bibliographies Web search tools that contain
  lists of links to Web pages.
• Many of these resources include summaries or
  reviews of Web pages.
• Also called
• Resource lists
• Subject guides
• Clearinghouses
• Virtual libraries

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Using Other Web Resources

• Web bibliographies may be called Web
  directories.
• are usually more focused on specific subjects
  than Web directories
• usually do not include a tool for searching
  within their categories.
• Web bibliographies can be very useful when you
  want to obtain a broad overview or a basic
  understanding of a complex subject area.
• Some Web bibliographies are general references,
  but most are more focused.
• Many Web bibliographies are created by librarians
  at university and public libraries.

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Boolean Logic andFiltering Techniques

• The most important factor in obtaining good
  results in a Web search is careful selection of
  the search terms you use.
• You can usually choose one or two words that will
  work well when the object of your search is
  straightforward.
• More complex search questions require more
  complex queries, which you can use along with
  Boolean logic, search expression operators, or
  filtering techniques, to broaden or narrow your
  search expression.

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Boolean Operators

• Boolean algebra was developed by George Boole, a
  nineteenth century British mathematician.
• Boolean operators, or logical operators, specify
  the logical relationship between the elements
  they join.
• Three basic Boolean operatorsAND, OR, and
  NOTare recognized by most search engines.
• You can use these operators in many search
  engines by including them with search terms.

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Boolean Operators
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Other Search Expression Operators

• A precedence operator, also called an inclusion
  operator or a grouping operator, clarifies the
  grouping within a complex expression and is
  usually indicated by the parentheses symbols.
• A location operator, or proximity operator, lets
  you search for terms that appear close to each
  other in the text of a Web page. The most common
  location operator offered in Web search engines
  is the NEAR operator.

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Wildcard Characters

• Wildcard character
• allows you to omit part of a search term.
• most search engines support some use of a
  wildcard character in their search expressions.
• many search engines recognize the asterisk () as
  the wildcard character.

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Search Filters

• Search filter
• eliminates Web pages from a search.
• the filter criteria can include such Web page
  attributes as language, data, domain, host, or
  page component.
• many search engines allow you to restrict your
  search by using them.

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Complex Searches

• Most search engines implement many of the
  operators and filtering techniques you have
  learned about.
• Some search engines provide separate advanced
  search pages for these techniques.
• Some search engines allow you to use advanced
  techniques such as Boolean operators on their
  simple search pages.

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Using AltaVistaAdvanced Search

• Open the AltaVista search engine in your Web
  browser.
• Select the Advanced Search option.
• Formulate and enter a suitable search expression.
• Click the Find button.
• Evaluate the results and, if necessary, revise
  your search expression.

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Using AltaVista Advanced Search

• See Figure 3-19, p. WEB 182

Complex search in AltaVista for the search
expression Germany AND (trade or treat) AND
agricult
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Filtered Search in Ask Jeeves

• Open the Ask Jeeves search engine page in your
  Web browser.
• Select the Advanced Options link.
• Formulate and enter a suitable search expression.
• Set any filters you want to use for the search.
• Click the Ask button.
• Evaluate the results and, if necessary, revise
  your search expression.

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Filtered Search in Ask Jeeves
Advanced search page in Ask Jeeves for the search
expression rice harvest Filtered to search only
for pages from Southeast Asia and modified in the
last six months

• See Figure 3-20, p. WEB 184

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Filtered Search in Google

• Open the Google search engine page in your Web
  browser.
• Click the Advanced Search link.
• Formulate and enter suitable search expression
  elements.
• Formulate and set appropriate search filters.
• Click the Google Search button.
• Evaluate the results and, if necessary, revise
  your search expression.

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Filtered Search in Google
Advanced search page in Google for the search
expression Finland School of Economics Filtered
to search only for pages in English and from the
TLD .fi.

• See Figure 3-22, p. WEB 187

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Search Engines withClustering Features

• Vivísimo is a search engine that uses advanced
  technology to group its results into clusters.
• The clustering of results provides a filtering
  effect.
• The filtering is done automatically by the search
  engine after it runs the search.

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Obtaining Clustered Search Results Using Vivísimo

• Open the Vivísimo search engine page in your
  browser.
• Formulate and enter a suitable search expression.
• Click the Search button.
• Evaluate the results and, if necessary, revise
  your search expression.

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Obtaining Clustered Search Results Using Vivísimo

• See Figure 3-24, p. WEB 190

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Future of Web Search Tools

• Most search engines cannot search the deep Web
  (hidden Web or invisible Web).
• static Web page an HTML file that exists on a
  Web server
• dynamic Web page a Web page generated as a
  result of a users query
• dynamic Web pages are not stored permanently on a
  Web server and cannot be found by bots
• much of the content on dynamic Web pages is
  accessible only by logged in users
• Work on natural language interfaces continues as
  search engine sites strive to make the job of
  searching even easier for users.

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Using People to EnhanceWeb Directories

• About.com hires people with expertise in specific
  subject areas to create and manage their Web
  directory entries in those areas.
• The Open Directory Project uses the services of
  more than 40,000 volunteer editors who maintain
  listings in their individual areas of interest.
• offers the information in its Web directory to
  other Web directories and search engines at no
  charge
• many major Web directories, search engines, and
  metasearch engines regularly download and store
  the Projects information in their databases.

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Evaluating the Validity and Quality of Web
Research Resources

• Web info seldom subjected to review processes
  that are standard practice in print publishing.
• Risks of obtaining and relying on inaccurate or
  unreliable information can be significant.
• Reduce your risk -- carefully evaluate the
  quality of any Web resource on which you plan to
  rely for information related to an important
  decision.
• Evaluate on the Web pages authorship, content,
  and appearance.

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Author Identity and Objectivity

• Web pages should identify the author and present
  the authors background information and
  credentials.
• Check secondary sources for corroborating
  information.
• Author contact information should be provided.
• Examine the domain identifier in the URL.
• Consider whether the qualifications presented by
  the author pertain to the material that appears
  on the Web site.
• Information about the authors affiliations
  should be provided.

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Content

• Determine timeliness of the content by checking
  the publication date.
• Read the content critically and evaluate whether
  the included topics are relevant to the research
  question at hand.
• Determine whether important topics or
  considerations were omitted.
• Assess the depth of treatment the author gives to
  subject.

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Form and Appearance

• Many pages that contain low-quality or incorrect
  information are poorly designed and not well
  edited.
• A Web page that contains spelling errors might
  indicate a low-quality resource.
• Loud colors, graphics that serve no purpose, and
  flashing text are all Web page design elements
  that often suggest low-quality resource.

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Evaluating the Quality of a Web Site

• Open the Web page in your Web browser.
• Identify the author, if possible. If you can
  identify the author, evaluate his or her
  credentials and objectivity.
• Examine the content of the Web site.
• Evaluate the sites form and appearance.
• Draw a conclusion about the sites overall
  quality.

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Summary

• Formulate specific and exploratory research
  questions.
• Use a structured Web search process to find
  information on the Web.
• Develop search expressions and used them in
  search engines, Web directories, and metasearch
  engines.

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Summary

• Boolean operators, precedence operators, and
  location operators how they work in several
  major search engines.
• Wildcards in search expressions.
• Some filtering techniques to narrow your search
  results.

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Summary

• You learned how to evaluate the validity and
  reliability of a Web page by using information
  about author identity and objectivity.
• You learned how to evaluate the validity and
  reliability of a Web page by evaluating content,
  form and appearance.