unit 3 web search engines. can you find the answers? n connect to google google n search for items...
Post on 22-Dec-2015
220 views
TRANSCRIPT
Can You Find the Answers?Can You Find the Answers?
Connect to Connect to GoogleGoogle Search for items on Iran Search for items on Iran Records ________Records ________ Combine Iran with nuclear weaponsCombine Iran with nuclear weapons Rec _______Rec _______ Combine Iran with the phrase Combine Iran with the phrase
nuclear weaponsnuclear weapons Rec _______Rec _______ Use Advanced Search:Use Advanced Search: Combine Iran with the phrase Combine Iran with the phrase nuclear weaponsnuclear weapons
so that all the words appear in title of so that all the words appear in title of
documentsdocuments Records ___Records ___
Unit 3Web Search Engines
Unit 3Web Search Engines
How People Search on the WebHow People Search on the Web What Are Search Engines?What Are Search Engines? How Search Engines Work How Search Engines Work What’s in Search Engines?What’s in Search Engines? How to Find Search EnginesHow to Find Search Engines Search BasicsSearch Basics
Three Ways People SearchThree Ways People Search
SurfSurf No direction, clear idea, issueNo direction, clear idea, issue Consult people, news, magazines, Web for ideasConsult people, news, magazines, Web for ideas
BrowseBrowse Have some idea, but vague, flexible, unclearHave some idea, but vague, flexible, unclear Consult reference sources, Web directories for Consult reference sources, Web directories for
direction, topic, themedirection, topic, theme Search in-depthSearch in-depth
Have defined topic, narrow focusHave defined topic, narrow focus Consult databases, search and metasearch enginesConsult databases, search and metasearch engines
What Are Search EnginesWhat Are Search Engines
SoftwareSoftware Captures web sites, pagesCaptures web sites, pages Indexes full-text of web pageIndexes full-text of web page Provides interface to search web pages Provides interface to search web pages
DatabaseDatabase Large, billions of pages (unlike directories)Large, billions of pages (unlike directories) Computer built (robots, spiders)Computer built (robots, spiders) No selectivity, no evaluationNo selectivity, no evaluation
How Search EnginesWorkHow Search EnginesWork
Spider comb, “capture” web pagesSpider comb, “capture” web pages Software builds databaseSoftware builds database Words from web pages “indexed”Words from web pages “indexed” Search interface finds words on pagesSearch interface finds words on pages Engine ranks, describes resultsEngine ranks, describes results How engines and directories differHow engines and directories differ
Spiders Comb, Capture Web PagesSpiders Comb, Capture Web Pages
Software decides which web pages to Software decides which web pages to collectcollect
Spiders check for updated pages Spiders check for updated pages Spiders remove dead sitesSpiders remove dead sites
Spider Software Builds DatabaseSpider Software Builds Database
Current web size: over 15 billion pagesCurrent web size: over 15 billion pages No engine’s database covers it allNo engine’s database covers it all
Google covers 22% (3.3 billion+)Google covers 22% (3.3 billion+) AlltheWeb covers 21% (3.2 million+)AlltheWeb covers 21% (3.2 million+) HotBot (Inktomi) covers 20% (3 billion+)HotBot (Inktomi) covers 20% (3 billion+) Teoma covers 10% (1.5 billion) Teoma covers 10% (1.5 billion)
Words from Web Pages “Indexed”
Words from Web Pages “Indexed”
““Index” means creating lists of words for Index” means creating lists of words for database and linking words to web pagesdatabase and linking words to web pages
Some index full text in documentSome index full text in document Some index part of textSome index part of text
First 100 words in documentFirst 100 words in document Words in abstract, or title of documentWords in abstract, or title of document
How indexing works affects search How indexing works affects search resultsresults
Search Interface Finds Web PagesSearch Interface Finds Web Pages
Provides keyword search boxProvides keyword search box
Offers simple or advanced searchingOffers simple or advanced searching Offers search options to affect results:Offers search options to affect results:
Most assume AND between words: Russian mafiaMost assume AND between words: Russian mafia Most accept “quotes” to search a PHRASE: Most accept “quotes” to search a PHRASE:
“Russian mafia”“Russian mafia” Most allow FIELD searches : ti:Russian mafiaMost allow FIELD searches : ti:Russian mafia
AlltheWebAlltheWeb
Engine Ranks, Describes Results Engine Ranks, Describes Results
Software lists most “relevant” items firstSoftware lists most “relevant” items first Word popularity: word repetitions, locationWord popularity: word repetitions, location Site popularity – visitations of web siteSite popularity – visitations of web site Link popularity – how often link citedLink popularity – how often link cited
Results describedResults described Few words to a paragraphFew words to a paragraph Sometimes stars, other indicators of Sometimes stars, other indicators of
relevancyrelevancy
How Engines and Directories Differ
How Engines and Directories Differ
Computers vs peopleComputers vs people Engine spiders not editors select documentsEngine spiders not editors select documents
Quantity vs qualityQuantity vs quality Engines big: want all, accept anythingEngines big: want all, accept anything Directories small: want “best” “important”Directories small: want “best” “important”
Technology vs human judgmentTechnology vs human judgment Engine software ranks, no human evaluationEngine software ranks, no human evaluation
Top Search Engines Top Search Engines
GoogleGoogle 3.3 billion+3.3 billion+ AlltheWebAlltheWeb 3.2 billion+3.2 billion+ HotBotHotBot (Inktomi) (Inktomi) 3 billion+3 billion+ TeomaTeoma 1.5 billion+1.5 billion+
Directories, Search Engines and Defaults
Directories, Search Engines and Defaults
If directories find little, they default to enginesIf directories find little, they default to engines Yahoo defaults to GoogleYahoo defaults to Google Open Directory defaults to GoogleOpen Directory defaults to Google Looksmart defaults to Inktomi (Hotbot)Looksmart defaults to Inktomi (Hotbot)
Some search engines borrow directoriesSome search engines borrow directories GoogleGoogle uses “Open Directory” uses “Open Directory”
Learn the source of information when using a Learn the source of information when using a directory search box or search engine’s directory search box or search engine’s directorydirectory
Metasearch EnginesMetasearch Engines
Technologies that search several search Technologies that search several search engines at the same timeengines at the same time
ProsPros
Increase results when search engine Increase results when search engine produce littleproduce little
Save time by searching several engines at Save time by searching several engines at onceonce
Show results of several engines on one Show results of several engines on one pagepage
ConsCons Retrieve too many hitsRetrieve too many hits Retrieve less relevant resultsRetrieve less relevant results
Do not individualize search syntax for each Do not individualize search syntax for each engineengine Do not know whether to use and, AND, +, OR, or, Do not know whether to use and, AND, +, OR, or,
cannot interpret phrases, etc.cannot interpret phrases, etc.
Exclude certain large engines like GoogleExclude certain large engines like Google
Top Metasearch EnginesTop Metasearch Engines
VivisimoVivisimo Categorizes results, narrows topicsCategorizes results, narrows topics
Ez2findEz2find Includes most major enginesIncludes most major engines
DogpileDogpile Refines results, covers major enginesRefines results, covers major engines
What’s In Search Engines?What’s In Search Engines?
Business, commercial informationBusiness, commercial information Organizational publicationsOrganizational publications Government resourcesGovernment resources Magazine, newspaper excerptsMagazine, newspaper excerpts Some scholarly informationSome scholarly information
Teaching materials, unpublished articlesTeaching materials, unpublished articles Books, articles whose copyright expiredBooks, articles whose copyright expired
What’s Not in Search EnginesWhat’s Not in Search Engines
Books under copyrightBooks under copyright Most Fiction, non-fiction in existence Most Fiction, non-fiction in existence
Journal, magazine, newspaper articlesJournal, magazine, newspaper articles Most current and past researchMost current and past research
Reference booksReference books Most recent, quality publicationsMost recent, quality publications
In shortIn short Bulk of human knowledge and researchBulk of human knowledge and research
How to Find Search EnginesHow to Find Search Engines
Word of mouth, hearsayWord of mouth, hearsay Newspaper, magazine articlesNewspaper, magazine articles Library web pagesLibrary web pages
Guides to search enginesGuides to search engines HyperResearchHyperResearch
Search BasicsSearch Basics
Identify, select keywordsIdentify, select keywords Effects of internet use on children Effects of internet use on children
Internet, children, effectsInternet, children, effects
Combine keywords to focus resultsCombine keywords to focus results Use OR, ANDUse OR, AND Use phrase searchingUse phrase searching Limit search to field like title or URLLimit search to field like title or URL
OrBroadens
OrBroadens
Retrieves an article if it contains Retrieves an article if it contains eithereither keyword keyword
Use to connect Use to connect similarsimilar words words Use to increase resultsUse to increase results
OR Expands Results
OR Expands Results
InternetInternet 1515 Internet OR WebInternet OR Web 50 50 Internet or Web or digital Internet or Web or digital 9090
ANDNarrows
ANDNarrows
Use to connect two Use to connect two differentdifferent ideas ideas AND between keywords means AND between keywords means bothboth
terms must be in recordterms must be in record Use to decrease resultsUse to decrease results
AND Reduces Results
AND Reduces Results
ChildrenChildren 2,956, 0002,956, 000 Children AND InternetChildren AND Internet
1,7561,756 Children AND Internet AND HomeworkChildren AND Internet AND Homework
Children internet homeworkChildren internet homework 26 26
AND, OR andSearch Engine Syntax
AND, OR andSearch Engine Syntax
Use Use helphelp or or tipstips AND, and, OR, or, “+” “-” ?AND, and, OR, or, “+” “-” ? Does engine default to AND or OR? Does engine default to AND or OR? Do AND or OR have to be upper case? Do AND or OR have to be upper case? Use ADVANCED SEARCH to learn optionsUse ADVANCED SEARCH to learn options
Is there a pull-down menu box?Is there a pull-down menu box? AND can mean “All the words” AND can mean “All the words” OR can mean “Any of the words”OR can mean “Any of the words”
Phrase SearchingPhrase Searching
Two words in consecutive orderTwo words in consecutive order Juvenile delinquency Russian mafiaJuvenile delinquency Russian mafia
How does computer recognize “phrase”?How does computer recognize “phrase”? Pull-down menu: EXACT PHRASEPull-down menu: EXACT PHRASE Quotation marks: Quotation marks: “drug abuse”“drug abuse”
Phrase searches reduce hits, improve Phrase searches reduce hits, improve relevancyrelevancy Russian mafia Russian mafia 23,234 23,234 ““Russian mafia” Russian mafia” 789 789
Field SearchingField Searching Common document “fields” Common document “fields”
Author, Title, Subject, Abstract, Text, URLAuthor, Title, Subject, Abstract, Text, URL Limits search to words in particular fieldsLimits search to words in particular fields
Learn syntax:Learn syntax:title: ti: url:title: ti: url: Ti: Russian mafiaTi: Russian mafia url: russianmafiaurl: russianmafia
Use ADVANCED SEARCHUse ADVANCED SEARCH Use pull-down menu (in the title, in the URL)Use pull-down menu (in the title, in the URL)
Reduces hits, improves relevancyReduces hits, improves relevancy Russian mafia (all the words) = 23,234Russian mafia (all the words) = 23,234 Russian mafia (in title) = 254Russian mafia (in title) = 254
Can You Find the Answers?Can You Find the Answers?
Connect to Connect to GoogleGoogle Search for items on Iran Search for items on Iran Records Records 11,00,00011,00,000 Combine Iran with nuclear weaponsCombine Iran with nuclear weapons Rec 7Rec 790,00090,000 Combine Iran with the phraseCombine Iran with the phrase
nuclear weaponsnuclear weapons Rec 428Rec 428,000,000 Use Advanced Search:Use Advanced Search: Combine Iran with the phrase Combine Iran with the phrase nuclear weaponsnuclear weapons
so that all the words appear in title of so that all the words appear in title of
documentsdocuments Records Records 274274