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Effective Web Searching. Dr. I.R.N. Goudar Visiting Professor-cum- Library Adviser University of Mysore Refresher Course UGC- Academic Staff College University of Mysore. Organization of the Web. Web is the totality of web pages stored on web servers

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effective web searching

Effective Web Searching

Dr. I.R.N. Goudar

Visiting Professor-cum- Library Adviser

University of Mysore

Refresher Course

UGC- Academic Staff College

University of Mysore

organization of the web
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
finding relevant documents on the web
Finding 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
three types of internet searching tools
Three Types of Internet Searching Tools
  • Subject Directories or Subject Trees such as Yahoo.
  • Search Engines such as Google, Teoma, and Alta Vista.
  • Metasearch Engines such as Dogpile and Mama, andixquick
limitations
Limitations
  • Anyone can put up a web page
  • Many pages not updated
  • No quality control
    • most sites not “peer-reviewed”
      • less trustworthy than scholarly publications
web directories guides
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
web directories guides1
Web Directories/ Guides...
  • Examples of general web directories:
    • Internet Public Library(http://www.ipl.org/)
    • Britannica’s “Web’s 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)
web directories guides2
Web Directories/ Guides...
  • Guides to directories:
    • WWW Virtual Library (www.vlib.org)
  • Subject-specific guides (subject gateways):
    • Intute (http://www.intute.ac.uk/)
    • IOP Physicsworld.com (http://physicsworld.com/)
    • Chemcenter(www.acs.com)
    • Programmers Heaven (www.programmersheaven.com)
  • Resource type guides:
    • Patents (www.european-patent-office.org)
    • Electronic journals (www.publist.com)
web search engines
Web Search Engines
  • 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
web search engines1
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)
    • Teoma (http://www.teoma.com/)
web search engines2
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.au:8000/MathSearch.html)
      • World Trade Locator (www.intl-tradenet.com)
    • Resource-specific search engines:
      • Patents (www.uspto.gov)
      • Journal articles (www.findarticles.com)
meta search tools
Meta Search Tools
  • Also know as multi-threaded search engine
  • Allows the user to search multiple databases simultaneously, via a single interface and return results in a uniform format
  • Presents a summary of the collected results from other search engines and directories
  • 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
meta search tools1
Meta Search Tools...

Search using multiple search engines

Search using a meta search tool

meta search tools2
Meta Search Tools...
  • Meta search tools (remote sites):
    • MetaCrawler (www.metacrawler.com)
    • Ixquick (www.ixquick.com)
    • Dogpile (www.dogpile.com)
  • Meta search tools (local, installable software):
    • Copernic (www.copernic.com)
    • LexiBot (www.completeplanet.com)
people finding tools
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.edu:6060/)
    • 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!)
web search strategies
Web Search Strategies
  • Search steps:
    • Analyze the search topic and identify the search terms, 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)
slide19

Google (www.google.com)

  • Enables users to search the Web, images, etc.
  • Features: PageRank, caching and translation, an option to find similar pages.
  • The focus is developing search technology.
  • Ranked #1 in the world
google
Google
  • Largest & Most Popular Search Engine
    • 8 Billion + Pages Indexed
  • Very Effective Advanced Search Features
    • Limit searches by domain, ie. Site:edu
    • Limit searches by format, ie. .pdf,
  • Specialized Search Tools
    • Images, Directory, Videos, Books, Scholar, News, Blogger
how google works
How Google works
  • BEFORE you search:“Crawls” pages on the public webCopies text & images, builds database
  • WHEN you search:Automatically ranks pages in your results
    • Word occurrence and location on page
    • Popularity - a link to a page is a vote for it
    • ~ 200 factors in all!
limit your search to
Limit your search to …
  • Web page titleintitle:hybridallintitle:hybrid mileage
  • Website or domainsite:whitehouse.gov “global warming”site:edu “global warming”
  • File typefiletype:pptsite:edu “global warming”
  • Definitionsdefine:pixeldefine:“due diligence”
on the results page
On the results page
  • Search box (use to modify)
  • “Cache”
  • “Related pages”
  • “Translate this page”
searching for pictures
Searching for Pictures
  • Searching for images is easy!
  • From the main page of the search engine, select images or pictures before entering your search term.
slide26

Google Scholar (scholarly literature=articles, books)

  • Google Books (books)
  • Google Directory (handpicked specific topical sites)
slide27
Beyond Google
  • Take advantage of human selectivityLibrarians’ Internet IndexInfoMineGoogle Custom Search Engines (CSE)
web directories guides3
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
web directories guides4
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
web search engines3
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 (-)
web search engines4
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)
web search engines5
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
web search engines6
Web Search Engines...
  • Example tutorials
    • Finding Information on the Internet: A tutorial (www.lib.berkeley.edu/TeachingLib/Guides/Internet/FindInfo.html)
    • How to search the world wide web: A tutorial for beginners and non-experts. David P. Habib and Robert L. Balliot. September, 1999 (204.17.98.73/midlib/tutor.htm)
web search engines7
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
web search engines8
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
top sites
Top Sites

The top sites on the web, ordered by Alexa Traffic Rank.

  • 1. Google
  • 2. Facebook
  • 3. Youtube
  • 4. Yahoo
  • 5. Live
  • 6. Baidu
  • 7. Wikipedia
  • 8. Blogger
  • 9. MSN
  • 10. Tencent
  • 11. Twitter
slide38

Google

- Enables users to search the Web, images, etc. - Features: PageRank, caching and translation, an option to find similar pages. - The focus is developing search technology.- Ranked #1 in the world according to the three- month Alexa traffic rankings.

yahoo
Yahoo! 
  • yahoo.com
  • Personalized content and search options. Chatrooms, free e-mail, clubs, and pager.
  • Ranked #4 in the world
  • The site is in the “Web Portals” category.
wikipedia
Wikipedia 
  • wikipedia.org
  • An online collaborative encyclopedia.
  • Wikipedia is ranked #7 in the world
  • It has been online for at least nine years.
  • The site's audience tends to be users who browse from school and work
meta search tools3
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
meta search tools4
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
people finding tools1
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 person’s name)
    • If person’s affiliation is known, Yahoo! Directory may be used to locate the institution and e-mail
web search strategies1
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
web search strategies2
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)
web search strategies3
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
sample web searches
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)
guides to search tools
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. Webster’s Big Page of Search Engines )
  • www.finderseeker.com (The search engine of search engines)
  • www.virtualfreesites.com (Over 1,000 specialised search engines)
keeping current
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)
web search engines9
Web Search Engines...
  • Demonstration of search engines:
    • Fastsearch (www.alltheweb.com)
    • Altavista (www.altavista.com)
    • Google (www.google.com)
    • Northernlight (www.northernlight.com)
meta search tools5
Meta Search Tools...
  • Demonstration:
    • MetaCrawler (www.metacrawler.com)
    • Ixquick (www.ixquick.com)
    • Dogpile (www.dogpile.com)
    • ProFusion (www.profusion.com)
sample web searches1
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
sample web searches2
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