Effective Web Searching

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Effective Web Searching
T.B. RajashekarNational Centre for Science
InformationIndian Institute of ScienceBangalore
- 560 012 (E-Mail raja_at_ncsi.iisc.ernet.in)
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Effective Web Searching

• How we use libraries and IR systems?
• Organization of the web
• Accessing web-based information key problems
• Tools for Information retrieval on the web
• Directories/ guides
• Search engines
• Meta search tools
• People finding tools
• Strategies for web searching
• Guides to search tools
• Keeping current

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How we use Libraries and IR Systems?

• Libraries
• How the documents are organised document types,
  classification system used
• Access tools catalogues, indexes, automated
  catalogues, access points
• Our information need (search topic) translate
  these in terms of organization scheme employed by
  the library
• Information Retrieval systems (e.g. bibliographic
  databases)
• How the database is organised, record content,
  fields, search elements
• Indexing and query language, thesaurus, Boolean
  logic, truncation, etc.
• Our information need formulated as a search
  expression using the query language

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Organization of the Web

• Adopt same strategy while searching the Web
• Understand web information architecture
• Understand the information access tools and the
  information access mechanisms they provide
• Represent our query in terms of mechanisms
  supported by these tools and search the web
• Web sites
• How the content is organised (document types,
  structuring and navigation)
• Searchable/indexable and non searchable/indexable
  content
• Structure of web pages
• Meta tags, page attributes (properties)

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Organization of the Web...

• Web is the totality of web pages stored on web
  servers
• Spectacular growth in web-based information
  sources and services
• Education and research
• Entertainment
• Business and commerce
• Personal home pages
• Estimated to contain over 1 billion indexable web
  pages
• Doubling each year
• Over 80 million web sites

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Accessing Web-based Information Key Problems

• Identification of sources (documents)
• No central card catalog
• Most web pages are not indexed in standard
  vocabulary, unlike library catalogues or journal
  article indexes
• Impossible to reach all related pages/ sites
  directly
• Need to use intermediate, resource finding tools

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Information Retrieval on the Web

• How to find relevant documents on the Web?
• Informal
• Browsing (and book marking for later use)
• Friends
• Print sources
• Discussion forums (mailing lists)
• Current awareness services (e.g. Scout Report)
• Guessing web site addresses!
• Formal (using information finding tools)
• Web directories/ guides
• Web search engines
• Meta-search tools
• Specialty search engines

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Web Directories/ Guides

• Also called as virtual libraries and Internet
  resource catalogues
• Organised collection of descriptions and links to
  Internet sources
• Organisation by subject categories
  (hierarchical) by resource type (patents,
  e-journals, institutes, etc.)
• Most use human experts for source selection,
  indexing and classification
• Some include reviews/ ratings of listed sites

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Web Directories/ Guides...

• Examples of general web directories
• Librarians Index to the Internet (www.lii.org)
• Britannicas Webs best sites
  (www.britannica.com)
• Infomine (infomine.ucr.edu)
• Scout Report Signpost (www.signpost.org)
• BUBL link (bubl.ac.uk/link)
• Yahoo (www.yahoo.com)
• Magellan (www.mckinley.com)
• Galaxy (www.galaxy.com)
• Looksmart (www.looksmart.com)
• Snap (www.snap.com)

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Web Directories/ Guides...

• Guides to directories
• WWW Virtual Library (www.vlib.org)
• Argus Clearinghouse (www.clearinghouse.net)
• Gogettem (www.gogettem.com/)
• Subject-specific guides (subject gateways)
• Edinburgh Engineering Virtual Library
  (www.eevl.ac.uk)
• Social Science Information Gateway (sosig.ac.uk)
• The Internet Pilot To Physics (physicsweb.org/TIPT
  OP)
• Chemcenter (www.acs.com)
• Programmers Heaven (www.programmersheaven.com)
• Resource type guides
• Patents (www.european-patent-office.org)
• Electronic journals (www.publist.com)

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Web Directories/ Guides...

• Most web directories support searching within
  categories and descriptions, in addition to
  browsing
• Advantages
• Access to high quality sources
• Do not contain redundant links
• Faster access to sources
• Disadvantages
• One needs to be aware of such directories/ guides
• May not be up-to-date
• May not be exhaustive
• Categories (subject hierarchy) varies across
  directories

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Web Directories/ Guides...

• When to use web directories/ guides?
• For broad/ general topics where keyword searching
  on search engines retrieves too many irrelevant
  sites
• When you want a few highly relevant sites and
  intention is not exhaustive/ comprehensive search
• When not to use web directories/ guides?
• For concept/ keyword searches
• Search terms are distinctive
• Effective directory/ guide usage
• Take advantage of the sub-search within
  categories, supported by most directories/ guides
• Join their mailing lists for automatic updates on
  new sites

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Web Directories/ Guides...

• Demonstration of directories/ guides
• Librarians Index to the Internet (www.lii.org)
• Britannicas Webs best sites
  (www.britannica.com)
• Scout Report Signpost (www.signpost.org)
• BUBL link (bubl.ac.uk/link)
• Yahoo (www.yahoo.com)
• WWW Virtual Library (www.vlib.org)
• Argus Clearinghouse (www.clearinghouse.net)

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Web Search Engines

• Just as AI journals index published literature,
  web search engines build a full-text index to web
  pages gathered from web sites and provide a
  keyword search interface to this index
• Spider programs periodically visit web sites and
  gather the web pages for indexing
• Also index web sites submitted by site developers
• A brief summary of the indexed web page is also
  prepared
• The index usually contains URLs, titles,
  headings, and other words from the HTML document

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Web Search Engines...

• The search engines provide a forms-based search
  interface for entering the queries
• Support simple and advanced search interfaces
• Search results are returned in the form of a list
  of web sites matching the query
• Some key features supported
• Phrase searching ( double quotes)
• Boolean searching (AND, OR, NOT)
• Implied Boolean Term inclusion (), term
  exclusion (-)

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Web Search Engines

• Key features
• Proximity searches (NEAR, ADJ, BEFORE, AFTER)
• Use of parentheses to group search terms
• Truncation searches (industr)
• Field-specific searching (Title, URL, Text)
• Natural language queries (Why is the sky blue?)
• Relevance ranking of search results
• Number of search terms
• Number of times each search term occurs
• Proximity of search terms
• Location of search terms (title, text)

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Web Search Engines

• Key features
• Sub-searching (searching within retrieved
  records)
• Case sensitivity
• Limit by language
• Limit by age of documents
• Limit by audio, video and image type
• Translation of search results (title and
  description)
• Limit by domain, host

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Web Search Engines...

• Examples
• Fastsearch (alltheweb.com)
• Altavista (www.altavista.com)
• Google (www.google.com)
• Northernlight (www.northernlight.com)
• HotBot (www.hotbot.com)
• Excite (www.excite.com)
• Lycos (www.lycos.com)
• InfoSeek Guide (www.infoseek.com)
• WebCrawler (www.webcrawler.com)
• Worldwide Web Worm (www.goto.com)

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Web Search Engines...

• Specialty search engines
• Country-specific search engines
• www.khoj.com
• www.123india.com
• Subject-specific search engines
• Chemfinder (www.chemfinder.com)
• Engineering Resources Online (www.er-online.co.uk)
  
• MathSearch (www.maths.usyd.edu.au8000/MathSearch.
  html)
• Netpart Company site locator (www.websense.com/lo
  cator.cfm)
• World Trade Locator (www.intl-tradenet.com)
• Resource-specific search engines
• Patents (www.uspto.gov)
• Journal articles (www.findarticles.com)

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Web Search Engines...

• Advantages of search engines
• Best suited for complex keyword/ concept searches
• Control over search search terms can be combined
  as required
• Searches can be limited to period of time,
  fields, source type,etc.
• Currency of information, made possible by regular
  addition by web spiders
• Exhaustive information can be retrieved (with
  lots of patience!)
• Disadvantages
• Time consuming
• False positives
• Search engines vary in terms of search
  techniques/ syntax
• Dead links, redundant links (same document gets
  displayed)
• Spamming (salting of pages)
• Higher ranking of paying sites

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Web Search Engines...

• Limitations of web search engines
• Poor retrieval effectiveness (relevance) as
  little vocabulary control is exercised by web
  site developers and the index engines
• Different search engines return different search
  results due to the variation in indexing and
  search process (40 non-overlap)
• None of the search engines come close to indexing
  the entire web, much less the entire Internet.
  Content not indexed
• PDF documents
• Content that requires log in
• Databases searched using CGI programs
• Web content on intranets behind fire walls

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Web Search Engines...

• Demonstration of search engines
• Fastsearch (www.alltheweb.com)
• Altavista (www.altavista.com)
• Google (www.google.com)
• Northernlight (www.northernlight.com)

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Meta Search Tools

• Exhaustive searches require use of more than one
  web search engine and familiarity with their
  search interface
• Meta search tools provide a common interface and
  conduct searches in many search engines
  simultaneously and return results in a uniform
  format
• Do not gather web pages, build indexes, accept
  URL additions, classify or review web sites
• Some features supported
• Duplicate hits removal
• Rank results
• Selection of search engine(s) to be used

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Meta Search Tools...
Search using multiple search engines
Search using a meta search tool
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Meta Search Tools...

• Meta search tools (remote sites)
• MetaCrawler (www.metacrawler.com)
• Ixquick (www.ixquick.com)
• Dogpile (www.dogpile.com)
• ProFusion (www.profusion.com)
• Meta search tools (local, installable software)
• Copernic (www.copernic.com)
• SearchPad (www.searchpad.com)
• LexiBot (www.completeplanet.com)

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Meta Search Tools...

• Advantages
• Query can be run across multiple search engines
• User needs to learn only the search interface of
  the meta search tool
• Better results retrieves top-ranking pages from
  individual search engines
• Disadvantages
• Unique features of individual search engines is
  lost
• Not exhaustive use only top results returned by
  search engines

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Meta Search Tools...

• When to use meta search tools?
• Need to be used cautiously
• Good for simple searches, particularly if search
  terms are distinctive or unique
• Good for testing with a few keywords and find
  which individual search engine returns good
  results
• Good for quick and dirty searching if you are
  in a hurry and want to find a few relevant sites
  quickly
• For complex searches, involving many search
  terms, Boolean logic, etc., it is better to use
  individual search engines

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Meta Search Tools...

• Demonstration
• MetaCrawler (www.metacrawler.com)
• Ixquick (www.ixquick.com)
• Dogpile (www.dogpile.com)
• ProFusion (www.profusion.com)

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People Finding Tools

• Register names and addresses and find e-mail
  addresses
• Examples
• Bigfoot (www.bigfoot.com)
• Peoplesearch (www.peoplesearch.net)
• Ahoy (ahoy.cs.washington.edu6060/)
• Four11 (www.four11.com)
• Switchboard (www.switchboard.com)
• Whowhere (www.whowhere.lycos.com/)
• Most search engines also support people searches
  (e.g. Altavista, Google, Yahoo!)

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People Finding Tools

• Using people finding tools
• Person should have registered in the tool(s)
• Searcher should know both surname and first name,
  else too many names will be retrieved
• Bias for U.S. based people
• Often, required e-mail cannot be retrieved
  through these tools
• Alternatively, any search engine may be used
  (phrase search using persons name)
• If persons affiliation is known, Yahoo!
  Directory may be used to locate the institution
  and e-mail

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Web Search Strategies

• Search steps
• Analyze the search topic and identify the search
  terms (both inclusion and exclusion), their
  synonyms (if any), phrases and Boolean relations
  (if any)
• Select the search tool(s) to be used (meta search
  engine, directory, general search engine,
  specialty search engine)
• Translate the search terms into search statements
  of the selected search engine
• Perform search
• Refine the search based on results
• Visit the actual site(s) and save the information
  (using File-Save option of the browser)

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Web Search Strategies

• Tips for effective web searching
• Broad or general concept searches start with
  directory-based services (want a few highly
  relevant sites for a broad topic)
• Highly specific or topics with unique terms/ many
  concepts use the search tools
• Go through the help pages of search tools
  carefully
• Gather sufficient information about the search
  topic before searching
• Spelling variations, synonyms, broader and
  narrower terms
• Use specific keywords, rare/unusual words are
  better than common ones

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Web Search Strategies...

• Tips for effective web searching
• Prefer phrase adjacency searching to Boolean
  (stuffed animal than stuffed and animal)
• Use as many synonyms as possible - search engines
  use statistical retrieval methods and produce
  better results with more query words
• Avoid use of very common words (e.g., computer)
• Enter search terms in lower case. Use upper case
  to force exact match (e.g. Light Combat
  Aircraft, LCA)
• Use More like this option, if supported by the
  search engine (e.g. Excite, Google)

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Web Search Strategies...

• Tips for effective web searching
• Repeat the search by varying search terms and
  their combinations try this on different search
  tools
• Enter most important terms first - some search
  tools are sensitive to word order
• Use the NOT operator to exclude unwanted pages
  (e.g. bio-data, resumes, courses)
• Go through at least 5 pages of search results
  before giving up the scan
• Select 2 or 3 search tools and master the search
  techniques

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Sample Web Searches

• Companies dealing with polymers
• Do not use search engines (too many irrelevant
  hits)
• Use directory sources (e.g. www.yahoo.com)
• Follow the categories
• Business and Economy
• Business-to-Business
• Chemicals
• Do a sub-search on Polymers
• Use specialty search engines (e.g.
  www.bizweb.com)

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Sample Web Searches...

• Web pages related to Light Combat Aircraft
• Keywords are unique
• Use Search Tools (e.g. www.altavista.com)
• Search for Light Combat Aircraft (phrase search
  in simple search interface)
• Use of double quotes will force the search engine
  to consider the set of keywords as a phrase
• Search can be limited to specific dates
• More refined search in advanced search interface
  Light Combat Aircraft AND India

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Sample Web Searches...

• Web sources related to simulation or modeling of
  activated sludge process
• This is a concept search - search tools are
  better
• Using Altavista, the query may be submitted as
• (simulat OR model) AND activated sludge
  process
• Note use of to cover word variations like
  simulated, simulate, models, etc.
• Note use of phrase form for activated sludge
  process

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Guides to Search Tools

• www.beaucoup.com (guide to 2,000 search engines,
  indices and directories)
• www.searchpower.com (a very comprehensive search
  engine directory - claims over 16,000 search
  engine listings!)
• www.123go.com/drw/search/search.htm (Dr.
  Websters Big Page of Search Engines )
• www.finderseeker.com (The search engine of search
  engines)
• www.virtualfreesites.com (Over 1,000 specialised
  search engines)

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Keeping Current

• AskScott (www.askscott.com) Provides a very
  comprehensive tutorial on search engines
• SearchEngineWatch (www.searchenginewatch.com) The
  site offeres information about new developments
  in search engines and provides reviews and
  tutorials.
• Botspot (www.botspot.com) Collection and guide
  to variety of bots (intelligent agents)

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Thank You!
raja_at_ncsi.iisc.ernet.in