CS276A Text Information Retrieval, Mining, and Exploitation. Lecture 9 5 Nov 2002

Transcription

1 CS276A Text Information Retrieval, Mining, and Exploitation Lecture 9 5 Nov 2002

2 Recap: Relevance Feedback Rocchio Algorithm: Typical weights: alpha = 8, beta = 64, gamma = 64 Tradeoff alpha vs beta/gamma: If we have a lot of judged documents, we want a higher beta/gamma. But we usually don t 2

3 Pseudo Feedback initial query apply relevance feedback retrieve documents label top k docs relevant documents top k documents 3

4 Pseudo-Feedback: Performance 4

5 Today s topics User Interfaces Browsing Visualization 5

6 The User in Information Access Find starting point Information need Formulate/ Reformulate Query Send to system Receive results Explore results User no Done? Stop yes 6

7 The User in Information Access Find starting point Information need Formulate/ Reformulate Query Send to system Receive results Explore results User Focus of most IR! no Done? Stop yes 7

8 Information Access in Context Information Access Analyze Synthesize High-Level Goal Done? User no Stop yes 8

9 The User in Information Access Find starting point Information need Formulate/ Reformulate Query Send to system Receive results Explore results User no Done? Stop yes 9

10 Starting points Source selection Highwire press Lexis-nexis Google! Overviews Directories/hierarchies Visual maps Clustering 10

11 Highwire Press Source Selection 11

12 Hierarchical browsing Level 0 Level 1 Level 2 12

13 13

14 Visual Browsing: Themescape 14

15 Browsing Starting point x x x x x x x x x x x x x x Credit: William Arms, Cornell Answer 15

16 Scatter/Gather Scatter/gather allows the user to find a set of documents of interest through browsing. Take the collection and scatter it into n clusters. Pick the clusters of interest and merge them. Iterate 16

17 Scatter/Gather 17

18 Scatter/gather 18

19 How to Label Clusters Show titles of typical documents Titles are easy to scan Authors create them for quick scanning! But you can only show a few titles which may not fully represent cluster Show words/phrases prominent in cluster More likely to fully represent cluster Use distinguishing words/phrases But harder to scan 19

20 Visual Browsing: Hyperbolic Tree 20

21 Visual Browsing: Hyperbolic Tree 21

22 Study of Kohonen Feature Maps H. Chen, A. Houston, R. Sewell, and B. Schatz, JASIS 49(7) Comparison: Kohonen Map and Yahoo Task: Window shop for interesting home page Repeat with other interface Results: Starting with map could repeat in Yahoo (8/11) Starting with Yahoo unable to repeat in map (2/14) Credit: Marti 22Hearst

23 Study (cont.) Participants liked: Correspondence of region size to # documents Overview (but also wanted zoom) Ease of jumping from one topic to another Multiple routes to topics Use of category and subcategory labels Credit: Marti 23Hearst

24 Study (cont.) Participants wanted: hierarchical organization other ordering of concepts (alphabetical) integration of browsing and search corresponce of color to meaning more meaningful labels labels at same level of abstraction fit more labels in the given space combined keyword and category search multiple category assignment (sports+entertain) Credit: Marti 24Hearst

25 Browsing Effectiveness depends on Starting point Ease of orientation (are similar docs close etc, intuitive organization) How adaptive system is Compare to physical browsing (library, grocery store) 25

26 Searching vs. Browsing Information need dependent Open-ended (find an interesting quote on the virtues of friendship) -> browsing Specific (directions to Pacific Bell Park) -> searching User dependent Some users prefer searching, others browsing (confirmed in many studies: some hate to type) You don t need to know vocabulary for browsing. System dependent (some web sites don t support search) Searching and browsing are often interleaved. 26

27 Searchers vs. Browsers 1/3 of users do not search at all 1/3 rarely search (or urls only) Only 1/3 understand the concept of search (ISP data from 2000) 27

28 Exercise Observe your own information seeking behavior WWW University library Grocery store Are you a searcher or a browser? How do you reformulate your query? Read bad hits, then minus terms Read good hits, then plus terms Try a completely different query 28

29 The User in Information Access Find starting point Information need Formulate/ Reformulate Query Send to system Receive results Explore results User no Done? Stop yes 29

30 Query Specification Recall: Relevance feedback Query expansion Spelling correction Query-log mining based Interaction styles for query specification Queries on the Web Parametric search Term browsing 30

31 Query Specification: Interaction Styles Shneiderman 97 Command Language Form Fillin Menu Selection Direct Manipulation Natural Language Example: How do each apply to Boolean Queries Credit: Marti 31Hearst

32 Command-Based Query Specification command attribute value connector find pa shneiderman and tw user# What are the attribute names? What are the command names? What are allowable values? Credit: Marti 32Hearst

33 Form-Based Query Specification (Altavista) Credit: Marti 33Hearst

34 Form-Based Query Specification (Melvyl) Credit: Marti 34Hearst

35 Form-based Query Specification (Infoseek) Credit: Marti 35Hearst

36 Credit: Marti 36 Hearst D irec Ma nipulatio VQUER (Jo ne 98) Spec.

37 Menu-based Query Specification (Young & Shneiderman 93) Credit: Marti 37Hearst

38 Query Specification/Reformulation A good user interface makes it easy for the user to reformulate the query Challenge: one user interface is not ideal for all types of information needs 38

39 Types of Information Needs Need answer to question (who won the game?) Re-find a particular document Find a good recipe for tonight s dinner Authoritative summary of information (HIV review) Exploration of new area (browse sites about Baja) 39

40 Queries on the Web Most Frequent on 2002/10/26 40

41 Queries on the Web (2000) 41

42 Intranet Queries (Aug 2000) 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 Source: Ray 42Larson

43 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 Source: Ray 43Larson

44 Query Specification: Feast or Famine Feast Specifying a well targeted query is hard. Bigger problem for Boolean. Famine 44

45 Parametric search Each document has, in addition to text, some meta-data e.g., Language = French Format = pdf Subject = Physics etc. Date = Feb 2000 A parametric search interface allows the user to combine a full-text query with selections on these parameters e.g., language, date range, etc. 45

46 Parametric search example 46

47 47 Parametric search example

48 Interfaces for term browsing 48

49 49

50 The User in Information Access Find starting point Information need Formulate/ Reformulate Query Send to system Receive results Explore results User no Done? Stop yes 50

51 Explore Results Determine: Do these results answer my question? Summarization More generally: provide context Hypertext navigation: Can I find the answer by following a link? Browsing and clustering (again) Browse to explore results 51

52 Explore Results: Context We can t present complete documents in the result set too much information. Present information about each doc Must be concise (so we can show many docs) Must be informative Typical information about each document Summary Context of query words Meta data: date, author, language, file name/url Context of document in collection Information about structure of document 52

53 Context in Collection: Cha-Cha 53

54 Category Labels Advantages: Interpretable Capture summary information Describe multiple facets of content Domain dependent, and so descriptive Disadvantages Do not scale well (for organizing documents) Domain dependent, so costly to acquire May mis-match users interests Credit: Marti 54Hearst

55 Evaluate Results Context in Hierarchy: Cat-a-Cone 55

56 Explore Results: Summarization Query-dependent summarization KWIC (keyword in context) lines (a la google) Query-independent summarization Summary written by author (if available) Exploit genre (news stories) Sentence extraction Natural language generation 56

57 Evaluate Results Structure of document: SeeSoft 57

58 Personalization User Query Outride Personalized Search System Interests Query Augmentation Intranet Search Demographics Result Processing Click Stream Search History Result Set Web Search Application Usage! " 58

59 59

60 & " How Long to Get an Answer? O u t r i d e G o o g l e 8 1 Y a h o o! E x c i t e A O L ! $1 & 0 -, (-/. )+* ' ( % $ # $! "

61 Search Engine User Actions Difference (%) Outride 11.2 Google Yahoo! AOL Excite Average Table 1. User actions study results. Experienced Users Novice Users Overall Engine Expert Time Rank Novice Time Rank Average Rank % Difference Outride 32.8 (1) 45.1 (1) 38.9 (1) 0% AOL 92.3 (5) 87.0 (4) 89.6 (5) 130.2% Excite 75.7 (3) 91.3 (5) 83.5 (4) 114.5% Google 72.5 (2) 78.4 (3) 75.4 (2) 93.7% Yahoo! 85.1 (4) 76.9 (2) 81.0 (3) 107.9% Table 2. Overall timing results (in seconds, with placement in parenthesis). 61

62 J M ED ' 62 C = >< = >< =? 8 =< 9;: N H F L K I J K HI G F Others Outride Novice Experts 4443 " %2 '1. -).0/ *,+ ( &% # ) $% " #!

63 Performance of Interactive Retrieval 63

64 Boolean Queries: Interface Is sues Boolean logic is difficult for the average user. Much research was done on interfaces facilitating the creation of boolean queries by non-experts. Much of this research was made obsolete by the web. Current view is that non-expert users are best served with non-boolean or simple +/- boolean (pioneered by altavista). But boolean queries are the standard for certain groups of expert users (eg, lawyers). 64

65 User Interfaces: Other Issues Technical HCI issues How to use screen real estate One monolithic window or many? Undo operator Give access to history Alternative interfaces for novel/expert users Disabilities 65

66 Take-Away Don t ignore the user in information retrieval. Finding matching documents for a query is only part of information access and knowledge work. In addition to core information retrieval, information access interfaces need to support Finding starting points Formulation/reformulation of queries Exploring/evaluating results 66

67 Exercise Current information retrieval user interfaces are designed for typical computer screens. How would you design a user interface for a wallsize screen? 67

68 Resources MIR Ch Donna Harman, Overview of the fourth text retrieval conference (TR EC 4), National Institute of Standards and Technology. Cutting, Karger, Pedersen, Tukey. Scatter/Gather. ACM SIGIR. Hearst, Cat-a-cone, an interactive interface for specifying searches and viewing retrieving results in a large category hierarchy, ACM SIGIR. 68