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  • 1. Search EnginesSearching More Effectively
  • 2. What is a search engine? Multiple servers that run a program called a spider or a crawler Crawlers build an index of web sites They follow the links on the website, and crawl those pages You can search the index by keyword matching Search engines don’t search the web, they search the index, so current events may not be indexed yet
  • 3. Surfing the Index Search engines don’t search the web, they search the index, so current events may not be indexed yet
  • 4. Directories can often be more fruitful than search engines Because directories are created by people and not programs... They are smaller but reflect evaluated material instead of all of the web They are even less likely to be up to date They usually take you to the front door of a website They are organized in a thoughtful manner so you can browse
  • 5. Directory Example Open Directory Project It helps you to think logically about the information you need—the structure is already there, you just have to follow it
  • 6. Popular Search Engines  Google  AltaVista  Yahoo  Alltheweb  MSN  DogPile
  • 7. Number of pages indexed The more pages indexed, the more likely you are to find what you need Hard to find a needle in a haystack if the haystack is dumped on your head Google— 4.3 Billion Yahoo— 3.2 Billion Teoma— 1 Billion AltaVista and AllTheWeb—Acquired by Yahoo and no longer available Source: Infopeopleproject.org
  • 8. Google’s Index Half the searchable web, so perhaps 8 billion searchable pages are out there
  • 9. What do search engines not search? Private Databases • Not fixed URLs • Professional, academic • Example at the end of presentation (MERLOT) Ask Jeeves only lists customers that pay to have their site indexed
  • 10. Market Share comScore Media Metrix Search Engine Ratings
  • 11. Which sites use what engine?  Google uses Google owned by Google  Yahoo uses Yahoo owned by Yahoo, but they used to use Google, and they did recently acquire Inktomi  AOL uses Google & Open Directory and owned by AOL  AltaVista uses Open Directory and Yahoo and owned by Yahoo  AlltheWeb uses and is owned by Yahoo  HotBot uses Google owned by Lycos
  • 12. Why do we care?If two sites use the same engine, you’ll get the same results comScore Media Metrix Search Engine Ratings
  • 13. Two sites, same results AltaVista—apple pie AltaVista found 2,410,000 results Yahoo.com--Results 1 - 10 of about 2,410,000 for apple pie
  • 14. What does that mean?Because there are basically twoforces now in the search engineworld, based on market share, indexsize and unique searchingtechnologies, general searches arebest done at either Yahoo or Google
  • 15. How does Google match websites? Page Rank • Google interprets a link from page A to page B as a vote by page A for page B. It also analyzes the page that casts the vote. If it’s important page (many links to it), its vote counts more heavily Text Matching • A page has to be both important (Page Rank) and relevant (text-matching) to be at the top of the list
  • 16. Matching (continued) When engines rank results related to text matching, the location and frequency of the text string plays into account Pages with the phrase apple pie will rank higher than pages that mention both terms separately Pages that mention apple pie repeatedly rank high than pages with fewer occurrences Pages with apple pie in the title of the page rank higher
  • 17. Title Tag When constructing a web page, the title tag is important Search engines look at them
  • 18. Example of Title Tag Code http://campuslife.wlu.edu Source code: <title>Orientation Programs--Washington and Lee University</title> In FrontPage, File/Save As/File Name/Title Google Search for New Page 1, 17,600,000
  • 19. Meta Tag Searching Google does not search Meta Tags, too much “meta tag spam” Inktomi was the last major search engine that used it, now they have been bought by Yahoo Teoma might use meta tags
  • 20. Meta Tag <head> <TITLE>Revisiting Meta Tags</title> <META NAME="authors" CONTENT=" Danny Sullivan"> <META NAME="date" CONTENT="20021205"> <META NAME="channel" CONTENT="internet technology"> <META NAME="description" CONTENT="Follow up to October 2002 article about the demise of the meta keywords tag."> </head>
  • 21. Keyword Searching Be as specific as you can Don’t use “car” if you can use “Toyota” Search engines have a hard time differentiating between differences in meaning, i.e., hard exam, hard cider, hard times, hard drive It can’t think for you—if you put in “heart attack”, it won’t show pages with “cardiac arrest”
  • 22. Boolean Searching George Boole, English Mathematician, Died 1864-logical combinatorial system AND, OR, NOT Used to get more targeted results Default Operator is AND at all major search engines, so if you type in apple pie, sites assume “apple AND pie”
  • 23. Using Boolean Operators at Google Default Operator is AND apple pie— 1,710,000 apple AND pie (+pie)—1,690,000, default operator message, but it does take into account word order Fewer results, perhaps a little more useful
  • 24. Boolean Operator OR apple OR pie—7,140,000 Use this if you don’t want to rule out too much Asthma, acute OR chronic
  • 25. Boolean Operator NOT apple NOT pie (–pie) What will NOT do to the search results? —816,000 Lessened results by half How could you use NOT to search for information about Bass fishing? bass NOT guitar (when you want the fish)
  • 26. Be Careful with “NOT” A search for apple pie NOT cobbler may remove useful results such as "Aunt Sarahs Better Than Cobbler Apple Pie"
  • 27. Synonyms ~apple ~pie (synonyms)—4,520,000
  • 28. Domain Restrict apple pie site:www.allrecipes.com—733More appropriate example: admissions information—3,730,000 admissions information site:www.wlu.edu 68www.wlu.edu, search
  • 29. Exact Search How do you get results that match exactly? Use quotation marks, i.e., “apple pie” 696,000 on Google
  • 30. AltaVista & Google Cool Feature Link—find out how many indexed pages link to your page http://www.altavista.com link:leechapel.wlu.edu AltaVista—92 (searches Yahoo) Google—33
  • 31. Cached Items Google “takes a picture” (indexes a site) As web sites often do, the site goes away You can still look at the old site through the cache www.google.com
  • 32. Meta Search Engine What is a Meta Search Engine? Search Engines that display results from several sites at once Dogpile--Google · Yahoo · Ask Jeeves About · LookSmart · Overture FindWhat Hmmm…Dogpile inserts sites that have paid for placement without telling into results from various search engines
  • 33. Safe Search Google—SafeSearch Filter—preferences Yahoo—SafeSearch Filter—preferences AltaVista—Settings, Family Filter, can set a password
  • 34. Advanced Settings Most search sites have a link for advanced settings, so you don’t have to remember the particular syntax for a particular type of search