Search Systems


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Search Systems

  1. 1. Information Architecture Search Systems
  2. 2. Does your site need search? ▫ Does your site have enough contents? ▫ Will this divert resources from navigation systems? ▫ Do you have time and knowledge to optimize the search system? ▫ Are there alternatives? ▫ Will your users bother with search?
  3. 3. Before you add a search system • Do not assume that a search engine alone will satisfy all users information needs • Should be used in addition to well structured navigation, not replacing navigation
  4. 4. Need a search system if… • When you have too much content to browse or content warrants it ▫ Eg – course catalog, research site, large site like Microsoft, real estate site • Fragmented subsites – Eg – UB • Site is a learning tool – Eg – web coding tutorials online • Dynamic site like a newspaper where articles are archived and only way to access them is to search
  5. 5. Search System Anatomy • Indexing by SE • Web Sites need to be SEO • Spiders • What is indexed – url, title, headings, keywords, content • Search interface • Boolean operators (and, or, not)
  6. 6. The Retrieval Process Search Search User Query Content Results Interface Engine Query Ranked Docs Operations Retrieved Docs DB Manager Module Text Database
  7. 7. Search Systems • Types of searches: ▫ Basic Search (also known as “keyword search” ▫ Advanced search: Use of search refinement and metadata search. • Search Engines are the software applications and foundation of search systems
  8. 8. Choosing what to search • Don’t have to index everything • If you conduct an inventory and analysis of your content you should have a good idea of what content is “good” • Silos – staff directories, sub sites, tech articles, books, etc… • Content components – title, author, etc..
  9. 9. Search Zones • Subsets of the site that have been indexed separately. ▫ Example ▫ Amazon does a great job of this • Can be: content type, audience, role, topic, geography, chronology, department
  10. 10. Types of Pages • Navigation pages – pages that help you browse a site • Destination pages – contain actual information • Want to make sure search results contain mostly destination pages
  11. 11. Search Systems • Selecting content components to index ▫ Take advantage of the site structure ▫ Components to index: • Body • Image Link • Title • Image alt text • URL • Description • Site name • Keywords • Link • Remote anchor text
  12. 12. Search Algorithms • There are many types of algorithms available. • The bottom line is to select the one that is appropriate for the type of search capabilities required by the user.
  13. 13. Set Theoretic •Fuzzy Classic Models •Extended Boolean •Boolean U •Vector space s Retrieval: •Probabilistic Algebraic e Adhoc •Generalized Vector r Filtering •Lat. Semantic Index T •Neural Networks Structured Models a •Non Overlapping s Lists Probabilistic k •Proximal nodes s •Inference Network Browsing •Belief Network Browsing •Language Models •Flat •Structure Guided •Hypertext
  14. 14. Pattern Matching Algorithms • Most common, matches a string that user entered • Depending on your user’s needs you have to emphasize recall or precision. • Recall - #relevant docs retrieved / #relevant docs in collection • Precision - #relevant docs retrieved / #total docs in collection
  15. 15. Pattern Matching Algorithms • Automatic Stemming – expands a term to include other terms that share the same root ▫ Eg: “word” gets you “password” • No Stemming – results contain just that word • Depends on the content you are indexing. Eg – course catalog
  16. 16. Other Approaches • Document Similarity - Allowing user feedback (more like this option) ▫ Can be done by re-querying w/o stopwords or automatically based on metadata • Collaborative filtering  Cited by  Active Bibliography (related docs)  Users who viewed this document also viewed  Similar documents based on text  Related documents based on co-citation
  17. 17. Query Builders • Tools that help SE performance – invisible to users ▫ Spell-checkers – Google’s “did you mean” ▫ Phonetic tools – sounds like ▫ Stemming tools – same stem results ▫ Natural language processing tools – how to ▫ Controlled vocabulary – include synonyms
  18. 18. Presenting Results • What to display? ▫ Title ▫ Summary ▫ Relevance score ▫ Other parts of the structure of docs ▫ Depends on your audience – more or less info – give users the option to see ‘detailed’ results if they choose – descriptive vs reprenstational • How many documents? ▫ Number of retrieved docs ▫ Number of results per page
  19. 19. Listing Results • Sorting  Alphabetically  Chronologically • Ranking  By relevance  By popularity  By users’ or experts’ ratings  By pay-for-placement
  20. 20. Listing Results • Grouping results: Clustering • Exporting results  Print or email results  Select a subset of results  Save search • No single approach is perfect – combine approaches
  21. 21. Search Interfaces • Factors that affect the interface design  User’s searching expertise  Type of results wanted  Type of information being searched  Amount of information being searched
  22. 22. Search Interface • The box: Simple and clear ▫ Good for users that don’t want to learn more about the search mechanism ▫ Placement of search matters on a site ▫ Put close to main navigation or near top of page ▫ Don’t be creative with button label
  23. 23. Advanced Search • Unveils search system functionality ▫ Field searching ▫ Date ranges ▫ Search zones • How often do you take advantage of these features?
  24. 24. Supporting Revision • What to do when users don’t get what they want?  Repeat search in results  Explain where results came from (what data was searched)  Explain what the user did (restate query, filters, sort order)  Integrate searching and browsing (product inventory)
  25. 25. Search Systems • When users get stuck ▫ Way too many results  Options to narrow search ▫ Zero results:  Offer means of revising the search  Search tips  A means of browsing (I.e. site map)  Human contact if searching & browsing don’t work
  26. 26. Search Systems • Commercial web site search available:  Verity Ultraseek  Altavista  Google  …… and many others
  27. 27. Search Systems • Free search options: ▫ Adding Google search to your site:  ▫ Open source software:  Lucene: (Jakarta Project)  MG: (Managing Gigabytes)
  28. 28. Discussion Questions • How has the search engine changed the way we use the web? • Where do you see it going in the future? • Search Engines – Pros / Cons • Articles