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Search Engines

You are searching a search engines database. Every result is at least ... Google has begun censoring sites for Internet users in China who are searching the Web...

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Search Engines

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    Slide 1:Search Engines

    Slide 2:WWW

    The “Public Web” Currently estimated at over ______ pages Private or “hidden” web: ____ that! No search engine can search it all… Google: covers less than ___ of public web

    Slide 3:Search Engines

    How do they work? Software programs called “______” or “web ______” Follow all links Record info about pages they visit in enormous ________

    Slide 4:Thus, you are NOT searching the web ________

    You are searching a search engines database Every result is at least a little bit “stale” Check _________ Settings…

    Slide 5:Your browser can contribute to “staleness,” too. Keeps a database of web pages, too: History ___________ Internet Files “_______” Faster to load a saved copy of a web page from _____________ than to retrieve a new copy of a web page from _____________

    Check Browser Settings…

    Slide 6:Coverage

    60% of a search engine’s data appears in ___________ search engine’s database. Only about 50% of a search engine’s data appears in “all” of the other search engines’ databases… Thus, 40% of a search engine’s data does not appear in ___________ search engine’s database… MORAL? Use one than one search engine…

    Slide 7:e.g. Dogpile www.dogpile.com Takes your search terms and searches ________________ for you…

    _______-search engines

    Slide 8:Ranking

    Q: When you search and multiple (!) pages result, what determines which pages get listed first? A: That search engine’s _________.

    Slide 9:Common Ranking Schemes

    ____________ Many factors and algorithms Number of times keywords of the search appear on the page Word appears in title? Word near top of page? _____________ How many OTHER pages link to the page containing the desired search term(s) ? A Combination of these two

    Slide 10:Other Ranking Factors

    “_____ for Rank” Some search engines let you ___ for prominence… “__________” Tricking the ranking scheme into favoring your web pages… Politics? Google has begun censoring sites for Internet users in China who are searching the Web…

    Slide 11:Key Searching Techniques

    Slide 12:Phrases

    Phrases in quotes e.g. “calvin college” Search on unique phrases Proper nouns “john calvin”

    Slide 13:Boolean Operators

    AND Usually _____ when you list multiple terms calvin college = calvin AND college

    Slide 14:Boolean Operators

    OR Usually must be _______ Sometimes also must be in ________ Shakespeare AND (theatre OR theater) for synonyms

    Slide 15:Boolean Operators

    _______! NOT Calvin NOT hobbes Google _______ sign: - Calvin -hobbes

    Slide 16:“_____ words”

    Common words ______ by search engine Google has _____ of them… Solution? Put in quotes – sometimes works Better: preceed with a plus: +who +are +you

    Slide 17:Field Limiting - ____

    Limit results to certain web page domain ____: site:calvin.edu site:.edu

    Slide 18:Google

    10 word limit Indexes only first 101KB of a Web page

    Slide 19:Yahoo!

    Must __________ OR, AND, or AND NOT. Also accepts parentheses No 10-word limit.

    Slide 20:Teoma

    http://www.teoma.com “Subject-Specific Popularity” ranking scheme How many __________ pages reference the page Optional follow-up steps after search results: REFINE: suggested terms to add to your search RESOURCES: communities, possibly directories, related to your search results ___________ database than Yahoo! And Google

    Slide 21:__________ Pages

    Search Engine Databases created by _________, not by “web crawling” software Thus, smaller databases, but _______ _______. Examples: LIBRARIANS' INDEX http://www.lii.org INFOMINE http://infomine.ucr.edu MEL (Michigan Elibrary) http://www.mel.lib.mi.us Academic Info http://www.academicinfo.net

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