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SIMS 202 Information Organization and Retrieval

SIMS 202 Information Organization and Retrieval. Prof. Marti Hearst and Prof. Ray Larson UC Berkeley SIMS Tues/Thurs 9:30-11:00am Fall 2000. Today. Introductions Course Overview Administrivia. Goals of the Course. Learn about:

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SIMS 202 Information Organization and Retrieval

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  1. SIMS 202Information Organization and Retrieval Prof. Marti Hearst and Prof. Ray Larson UC Berkeley SIMS Tues/Thurs 9:30-11:00am Fall 2000

  2. Today • Introductions • Course Overview • Administrivia

  3. Goals of the Course • Learn about: • Design, development and use of information storage and retrieval systems • Practical and theoretical foundations of information organization and analysis • Evaluation of information access systems • Cognitive and user-centric considerations • Hands-on experience with information systems

  4. Information Organization and Design Information Retrieval and the Search Process Two Main Themes

  5. Web Search Questions • What do people search for? • How do people use search engines? • How often do people find what they are looking for? • How difficult is it for people to find what they are looking for? • How can search engines be improved?

  6. What Do People Search for on the Web? • Study by Spink et al., Oct 98 • www.shef.ac.uk/~is/publications/infres/paper53.html • Survey on Excite, 13 questions • Data for 316 surveys

  7. What Do People Search for on the Web? Topics • Genealogy/Public Figure: 12% • Computer related: 12% • Business: 12% • Entertainment: 8% • Medical: 8% • Politics & Government 7% • News 7% • Hobbies 6% • General info/surfing 6% • Science 6% • Travel 5% • Arts/education/shopping/images 14% Something is missing…

  8. 4660 sex 3129 yahoo 2191 internal site admin check from kho 1520 chat 1498 porn 1315 horoscopes 1284 pokemon 1283 SiteScope test 1223 hotmail 1163 games 1151 mp3 1140 weather 1127 www.yahoo.com 1110 maps 1036 yahoo.com 983 ebay 980 recipes What do people search for on the web? • 50,000 queries from excite 1997 • Most frequent terms:

  9. Why do these differ? • Self-reporting survey • The nature of language • Only a few ways to say certain things • Many different ways to express most concepts • UFO, Flying Saucer, Space Ship, Satellite • How many ways are there to talk about history?

  10. 3351 bearfacts 3349 telebears 1909 extension 1874 schedule+of+classes 1780 bearlink 1737 bear+facts 1468 decal 1443 infobears 1227 calendar 989 career+center 974 campus+map 920 academic+calendar 840 map 773 bookstore 741 class+pass 738 housing 721 tele-bears 716 directory 667 schedule 627 recipes 602 transcripts 582 tuition 577 seti 563 registrar 550 info+bears 543 class+schedule 470 financial+aid Intranet Queries (Aug 2000)

  11. Intranet Queries • Summary of sample data from 3 weeks of UCB queries • 13.2% Telebears/BearFacts/InfoBears/BearLink (12297) • 6.7% Schedule of classes or final exams (6222) • 5.4% Summer Session (5041) • 3.2% Extension (2932) • 3.1% Academic Calendar (2846) • 2.4% Directories (2202) • 1.7% Career Center (1588) • 1.7% Housing (1583) • 1.5% Map (1393) • Average query length over last 4 months: 1.8 words • This suggests what is difficult to find from the home page

  12. An Example Search System:Cha-Cha • A system for searching complex intranets • Places retrieval results in context

  13. An Example Search System: Cha-Cha • Important design goals: • Users at any level of computer expertise • Browsers at any version level • Computers of any speed

  14. Search: Where to Start? • Guess words? • Search engine plunges you into the middle of a site/collection • Too many or too few results • No context • Use a directory? • If large, may be difficult/frustrating to navigate • Several ways to organize the information • May not reflect users’ needs • Solution: Integrate Browsing and Search

  15. How Cha-Cha Works • Crawl entire Intranet • Compute the shortest hyperlink path from a certain root page to every web page • Index and compute metadata for the pages • Using Cheshire II (by Ray Larson) • Run a user query. • Gather all the hits • Create a “directory” based on combining the shortest paths • Special graph algorithm removes redundant links and internal nodes

  16. Cha-Cha System Architecture store the documents crawl the web

  17. Cha-Cha System Architecture store the documents crawl the web create files of metadata Cheshire II

  18. Cha-Cha Metadata • Information about web pages • Title • Length • Inlinks • Outlinks • Shortest Paths from a root home page • Used to provide innovative search interface

  19. Cha-Cha System Architecture store the documents crawl the web create files of metadata Cheshire II

  20. Cha-Cha System Architecture store the documents crawl the web create a keyword index create files of metadata Cheshire II

  21. Creating a Keyword Index • For each document • Tokenize the document • Break it up into tokens: words, stems, punctuation • There are many variations on this • Record which tokens occurred in this document • Called an Inverted Index • Dictionary: a record of all the tokens in the collection and their overall frequency • Postings File: a list recording for each token, which document it occurs in and how often it occurs

  22. Cha-Cha System Architecture user query Cheshire II

  23. Responding to the User Query • User searches on “pam samuelson” • Search Engine looks up documents indexed with one or both terms in its inverted index • Search Engine looks up titles and shortest paths in the metadata index • User Interface combines the information and presents the results as HTML

  24. Cha-Cha System Architecture user query Cheshire II

  25. Cha-Cha System Architecture server accesses the databases Cheshire II

  26. Cha-Cha System Architecture results shown to user Cheshire II

  27. Cha-Cha System Architecture user query server accesses the databases results shown to user Cheshire II

  28. What hasn’t been explained here? • How documents are ranked • How queries are formed • How shortest paths are computed • How the system is built • … among other things! • This is just an introduction! Much more later.

  29. Retrieval The Search Process Content Analysis Tokenization, Zipf’s Law, Lexical Associations IR Implementation Term weighting and document ranking Vector space model Probabilistic model User Interfaces Overviews, query specification, providing context, relevance feedback Course Schedule

  30. Information Organization and Design Information Retrieval and the Search Process Two Main Themes

  31. Overview Example • Web site design • Incorporates many of the organizational issues we will be covering • Example taken from a study of professional designers, by Mark Newman

  32. Web Site Design • Information design • structure, categories of information • Navigation design • interaction with information structure • Graphic design • visual presentation of information and navigation (color, typography, etc.) Adapted from slide by Mark Newman

  33. Design Specialties • Information Architecture • includes management and more responsibility for content • User Interface Design • includes testing and evaluation Adapted from slide by Mark Newman

  34. Web Site Design Process Needs Assessment Conceptualization Preliminary Design Design Implementation Adapted from slide by Mark Newman

  35. Design Process: Preliminary Design (information/navigation design: schematic) Adapted from slide by Mark Newman

  36. Design Process: Preliminary Design (navigation design: storyboard) Adapted from slide by Mark Newman

  37. Web Site Design Process • Major design activities are: • Deciding on a set of categories that define the information content • Deciding how to represent these • Deciding on the navigation structure through the categorized content • Example: a movie listing website • There are similarities and differences to: • Database design • Thesaurus design

  38. Organization Overview Metadata and Markup Controlled Vocabularies, Classification, Thesauri Information Design Thesaurus Design Database Design Course Schedule

  39. Assignments and Exams • Approximately 9 short assignments (due within one week – ten days) • Sometimes “checked”, sometimes graded • One Midterm • Might be a project, might be an exam (TBA) • Final exam Monday Dec 11 • Grading: • Assignments: 40% • Not evenly weighted • Final: 25% • Midterm: 25% • Class Participation: 10%

  40. Readings • Course Reader • Will be available in about a week at Ned’s • (on Bancroft, across from the ASUC) • Textbooks • Modern Information Retrieval, Baeza-Yates and Ribiero-Neto (Eds.), Addison Wesley, 1999 • The Organization of Information, Arlene G. Taylor, Libraries Unlimited, 1999,

  41. Homework (!) • Read the handout (Borges and Dennett) • Write one or two paragraphs on • What is information, according to your background or area of expertise? • Due in class this Thursday, Aug 31.

  42. There is no “correct” definition Can involve philosophy, psychology, signal processing, physics Cookie Monster’s definition: “news or facts about something” Oxford English Dictionary information: informing, telling; thing told, knowledge, items of knowledge, news knowledge: knowing familiarity gained by experience; person’s range of information; a theoretical or practical understanding of; the sum of what is known What is Information?

  43. Next Time More on What is Information?

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