Transcript Tutorial 1

Tutorial 3:
Searching the Web
Objectives
• Session 3.1
– Determine whether a research question is specific
or exploratory
– Formulate an effective Web search strategy to
answer research questions
– Use Web search tools including search engines,
Web directories, metasearch engines, and Web
bibliographies effectively
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Objectives
• Session 3.2
– Apply Boolean logic and filtering techniques to
improve your Web searches
– Perform complex searches in search engines
– Use advanced search options in Web search
engines
– Assess the validity and quality of Web research
resources
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Session 3.1 Overview
How a Search Engine Works
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Types of Search Questions
• A specific question is a question that you can phrase
easily and one for which you will recognize the
answer when you find it
• An exploratory question is an open-ended question
that can be harder to phrase; it also is difficult to
determine when you find a good answer
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Types of Search Questions
• Finding Answers to Specific Questions
– Can be answered with a single fact or set of
information
– The search for the answer involves a process of
narrowing down the range of potential answers
you examine in each step
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Types of Search Questions
• Finding Answers to Specific Questions (continued)
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Types of Search Questions
• Finding Answers to Exploratory Questions
– Cannot be answered with a single fact or set of
information
– Search starts with general questions that lead to
other, less general questions
– Scope broadens as you gather information
pertinent to the exploratory question
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Types of Search Questions
• Finding Answers to Exploratory Questions (continued)
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Formulating Effective
Web Search Strategies
• For specific questions:
– Formulate and state your question
– Select the appropriate tool(s) to use in your search
– Translate your question into a search query
– Run the query and evaluate your results
– If results do not answer the question:
• Continue the search with a different search tool
• Revise and narrow the question and repeat the
process
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Formulating Effective
Web Search Strategies
• For exploratory questions:
– Formulate and state your question
– Select the appropriate tool(s) to use in your search
– Translate your question into a search query
– Run the query and evaluate your results
– If results do not answer the question, formulate
and state additional questions and repeat the
process until there is sufficient information to
answer the question
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Formulating Effective
Web Search Strategies
• An important part
of searching is
evaluating the
quality of the
search results
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Web Search Tools
• Web search tools include four broad categories of
sites:
– Search engines
– Directories
– Metasearch engines
– Other Web resources such as Web bibliographies
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Web Search Tools
• Understanding Search Engines
– A Web search engine is a Web site that finds other
Web pages that match a word or phrase you enter
– The word or phrase you enter in a search engine is
called a search expression or a query
– A search expression might also include
instructions that tell the search engine how to
search
– A basic search page includes a text box for
entering a search expression and a command
button to begin the search
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Web Search Tools
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Web Search Tools
• Understanding Search Engines (continued)
– A Web robot, also called a bot or a spider, is a
program that automatically searches the Web to
find new Web sites and update information about
old Web sites that are already in the database
– One of a Web robot’s more important tasks is to
delete information in the database when a Web
site no longer exists
– All search engines provide a series of results
pages, which are Web pages that list hyperlinks to
the Web pages containing text that matches your
search expression
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Web Search Tools
• Understanding Search Engines (continued)
– A hit is a Web page that is indexed in the search
engine’s database and that contains text that
matches a specific search expression
– A hyperlink to a Web page that no longer exists or
has been moved to another URL is called a dead link
– Web pages or Web sites that have a number of dead
links are said to suffer from link rot
– Most search engines label paid placement links as
“sponsored,” and they are called sponsored links
– If the advertising appears in a box on the page, it is
usually called a banner ad
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Web Search Tools
• Understanding Search Engine Databases
– A meta tag is 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
– Search engines that store a Web page’s full
contents are called full text indexing engines
– Many search engines omit stop words such as
and, the, it, and by from their databases
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Web Search Tools
• Understanding Search Engine Databases (continued)
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Web Search Tools
• Search Engine Features
– Page ranking is a way of grading Web pages by the
number of other Web pages that link to them
– Inbound links are the connections or links from
other pages
– Most search engines use stemming to search for
variants of keywords automatically
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Web Search Tools
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Web Search Tools
• Search Engine Features (continued)
– A natural language query interface allows users to
enter a question exactly as they would ask a person
that question
– The procedure of converting a natural language
question into a search expression is sometimes called
parsing
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Web Search Tools
• Using Directories and Hybrid Search Engine
Directories
– A Web directory is a listing of hyperlinks to Web
pages that is organized into hierarchical categories
– The combination of search engine and directory is
sometimes called a hybrid search engine
directory
– Yahoo! Directory includes 16 main categories
– The Open Directory Project uses the services of
more than 40,000 volunteer editors who maintain
listings in their individual areas of interest
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Web Search Tools
• Using Metasearch Engines
– A metasearch engine is a tool that combines the
power of multiple search engines
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Web Search Tools
• Using Web Bibliographies
– The Web includes Web bibliographies, another
category of resource for searching the Internet
– Web bibliographies are also called resource lists,
subject guides, clearinghouses, and virtual
libraries
– Can be very useful when you want to obtain a
broad overview or a basic understanding of a
complex subject area
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Session 3.2 Visual Overview
Evaluating Web Sites
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Using Logical Operators and
Filtering Techniques in Complex Searches
• Logical operators specify the relationship between
the elements they join
• The most commonly used logical operators in
complex Web searching are Boolean operators,
named for George Boole, a nineteenth-century
British mathematician who developed a system of
logic called Boolean algebra
• Boolean algebra is the branch of mathematics and
logic in which all values are reduced to one of two
values (usually true or false)
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Using Logical Operators and
Filtering Techniques in Complex Searches
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Using Logical Operators and
Filtering Techniques in Complex Searches
• Other Search Expression Operators
– A precedence operator, also called an inclusion
operator or a grouping operator, establishes
grouping levels within a complex expression
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Using Logical Operators and
Filtering Techniques in Complex Searches
• Other Search Expression Operators (continued)
– A location operator, or proximity operator, lets
you search for terms that appear close to each
other in the text of a Web page
• Wildcard Characters
– A wildcard character allows you to omit part of a
search term
– The asterisk (*) is the most common wildcard
character
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Using Logical Operators and
Filtering Techniques in Complex Searches
• Search Filters
– Many search engines allow you to restrict your
search by using search filters
– A search filter eliminates Web pages from search
results
– Filter criteria can include such Web page
attributes as language, date, domain, host, or
page component (URL, hyperlink, image tag, or
title tag)
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Performing Complex Searches
• Most search engines implement many operators and
filtering techniques; the way in which they are
applied differs
• Using Exalead to Perform a Boolean Search
– Exalead is a search engine that allows the use of
several Boolean and precedence operators
– To create an effective search expression, you must
identify search terms that might lead you to
appropriate Web pages
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Performing Complex Searches
• Using Exalead to Perform a Boolean Search (continued)
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Performing Complex Searches
• Filtered Search in Google
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Performing Complex Searches
• Using Search Engines with Clustering Features
– Some search engines group their search results
into clusters
– The clustering of results is similar to a filtering
effect; however, the filtering is done automatically
by the search engine after it runs the search
– None of the search results are discarded; they are
simply sorted into multiple categories, or clusters
– Clustering can be especially effective when a word
in the search expression has multiple meanings
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Exploring the Deep Web
• A static Web page is an HTML file that exists on a
Web server computer
• Many Web sites store information in a database, and
when a user submits a query, the site’s Web server
searches the database and generates a Web page on
the fly that includes information from the database
• These generated pages are called dynamic Web
pages
• Deep Web, hidden Web, and invisible Web are
terms for the information contained in the databases
that some Web sites use to generate dynamic pages
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Evaluating Web Research
Resources
• When you are searching the Web for an answer to a
serious research question, the risks of obtaining and
relying on inaccurate or unreliable information can
be significant
• Reduce risks by evaluating carefully the quality of any
Web resource; you can evaluate four elements of any
Web page:
– Authorship
– Ownership
– Content
– Appearance
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Evaluating Web Research
Resources
• Authorship, Expertise, and Objectivity
– Consider whether the qualifications presented
pertain to the material that appears on the Web
site
– Author info should include the author’s affiliations
with organizations related to the site information
• Web Site Ownership and Objectivity
– Most Web sites include information about
ownership on their About pages
– Examine the domain identifier in the URL
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Evaluating Web Research
Resources
• Accuracy, Relevance, Scope, and Objectivity of Content
– Determine the timeliness of the content
– Read with a critical eye and evaluate whether the
included topics are relevant
– Evaluate the scope of the site; determine whether
important topics or considerations are omitted
– Confirm the Web page content’s objectivity
• Form and Appearance
– A legitimate source of accurate information usually
presents its information in a professional form
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Evaluating Web Research
Resources
• Evaluating the Quality of a Web Page
– Identify the author, and his or her credentials and
objectivity
– Examine Web site content for accuracy, relevance,
scope, and objectivity
– Evaluate the site’s form and appearance to
determine quality and appropriateness
• Evaluating Wikipedia Resources
– Wikipedia is a Web site that hosts a communityedited set of online encyclopedias
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