Post on 19-Jan-2016
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SEARCHING FOR TRUTH
Locating Information on the WWW
chapter5
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Characteristics of Directories
• Topical lists of Internet Resources• arranged in a hierarchical way• differ from search engines: humans maintain
directories and search engines rely on spiders or robots to crawl the Internet for links.
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Characteristics of Directory
• Ask the following questions:– Who selects the included Web resources?– Who categorizes the Web pages and sites?– How are the results displayed?– Are the sources rated? annotated? reviewed?
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Strengths of Directories
• fewer resources than search engine databases
• provide rating or annotation of resources• increase probability of finding relevant results
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Disadvantages
• arbitrary hierarchical arrangements• infrequent updates• subjectivity of rating and annotating
resources
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Using the Yahoo Directory
• Go to Yahoo• click on Science• follow appropriate links to Human Genome
Projects.
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Using Directory Search
• Go to Yahoo home page• click on search and enter “Human genome
project”
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The First Step: Evaluating Your Information Needs
• Types of information most likely to be found on the Internet
• Some reasons why the Web won’t have everything you’re looking for
• Choosing the best tool to start with• A checklist to help you choose the right tool
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Finding Information Gems in Virtual Libraries
• Virtual libraries are directories that contain collections of evaluated resources that have carefully selected by information specialists.
• Subject guides, reference works, and specialized databases, are most likely found in virtual libraries.
• Two popular virtual libraries are the Internet Public Library, http://ipl.org, and the Librarians’ Index to the Internet, http://lii.org.
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Searching the World Wide Web: Using Search Engines
• Search engines use computer programs called spiders or robots to gather information on the Internet.
• The information is kept in a database that is searchable.
• Two popular search engines are Google, http://www.google.com, and AltaVista, http://altavista.com.
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Search Engine Similarities
• Search engines list results by some type of relevancy ranking scheme.
• Two common search features are Boolean searching and phrase searching.
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Search Engine Differences
• Size of the database• Search options• Update frequency• Ranking of search results• Special features (images, news, and so forth)
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Using Several Search Engines Simultaneously: Meta-search Tools
• Some allow you to search several search engines simultaneously.
• Some supply lists of databases that can be searched directly from their pages.
• May provide a good way to keep up with new search engines.
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Task
• Explore the Directory of NPR – describe its organization
• Now look at a web library. Describe its organization
• Find the Kelly book value of my car: a 1998 Honda Civic CX.
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Content Issues: Pornography, Free Speech, Censorship, and Filtering
• Free speech vs. censorship• Communications Decency Act of 1996• Filtering and blocking devices
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UW libraries Top 20 Databases with links
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Summary links for UW libraries reference materials
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Top level, second level and third level classifications of a collection
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National Public Radio (NPR) home page www.npr.org
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The NPR home page Programming pull-down menu
What are the top level
classifications?
What are the top level
classifications?
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The NPR programming hierarchy tree
How many levels in the hierarchy?
How many levels in the hierarchy?
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The Google search engine’s advanced search view
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Restricting the Thai restaurants “hits” by eliminating any page containing the word review.
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Making Effective Queries
• Queries use the three logical operatorsworda AND wordb -- both words must appear
worda OR wordb -- either word may appear
NOT worda -- the word is prohibited from appearing
• Google has separate windows for each• When 1 window is available, write a formula
(Lincoln OR Jefferson) AND NOT Memorial
worda wordb
Which parts of the diagram do the operators
cover?
Which parts of the diagram do the operators
cover?
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The Burmese mountain dog page
Does this page seem
legitimate?
Does this page seem
legitimate?