1 CS 430 / INFO 430 Information Retrieval Lecture 15 Usability 3

2 Course Administration Midterm Examination Collect answer books at end of class or from reception at 301 College Avenue Average grade = 24.5/30 Assignment 2 We hope to the grades and comments this afternoon. Assignment 3 Due: Monday November 8 The assignment will be posted within the next few days

3 Course Administration Seminar next Tuesday Amit Singhal, Google Hollister B14, 4:30 to 5:30 This talk will describe the challenges in running a very large web search service, with hundreds of millions of hits per day. Amit Singhal holds a Ph.D. from Cornell computer science, where he was a student of Gerald Salton

4 Browsing: The Human in the Loop Search index Return hits Browse repository Return objects

5 Browsing in Information Space x x x xx x x x x x x x x x Starting point Effectiveness depends on (a) Starting point (b) Effective feedback (c) Convenience

6 Convenience of Browsing Rapid access to materials Physical objects Library or large private collection Similar items stored close together (classification) Online information Rapid delivery to desktop good system performance no administrative delays (authentication) Human skills and knowledge augment and extend the automatic methods of searching

7 Convenience of Browsing If the documents are accessible online, user can browse content. This can compensate for weaknesses in the underlying search system, e.g., the difficulty of indexing Web documents Otherwise, the user can browse substitutes, e.g., catalog records, subject hierarchies, etc. This puts heavy demands on the precision of the underlying search system

8 Browse: Catalog Record

9 Hierarchical browsing Level 2 Level 1 Level 0

10 The Yahoo Interface

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12 The Yahoo Interface The Yahoo interface is cluttered and unattractive, yet Yahoo is one of the most successful of all web sites. Why is this interface successful? Very many branches from a single web page saves the need for hierarchy of menus. Simple html markup ensures that the page renders quickly and accurately on all browsers. Slow changes over the years means that users are familiar with it.

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14 Browsing the Content of Indexes Show the users the terms that occur in indexes, such as subject headings. Example: Library of Congress:American Memory

15 Broad categories

16 Subject headings grouped

17 Subject headings used in index

18 Browsing by Filtering and Sorting Filters allow users to reject categories of information. Sorting by various criteria allows users to organize information for rapid scanning Example: Research Libraries Group Cultural Materials

19 Browse everything

20 Filter "New York"

21 Sort "date"

22 Information Visualization Human eye is excellent in identifying patterns in graphical data. Trends in time-dependent data. Broad patterns in complex data. Anomalies in scientific data. Visualizing information spaces for browsing.

23 Alphabetic list

24 Graphical display

25 Visualization within Documents: Tilebars The figure represents a set of hits from a text search. Each large rectangle represents a document or section of text. Each row represents a search term or subquery. The density of each small square indicates the frequency with which a term appears in a section of a document. Hearst 1995

26 Semantic Zooming: Pad++ Concept. A large collection of information viewed at many different scales. Imagine a collection of documents spread out on an enormous wall. Zoom. Zoom out and see the whole collection with little detail. Zoom in part way to see sections of the collection. Zoom in to see every detail. Semantic Zooming. Objects change appearance when they change size, so as to be most meaningful. (Compare maps.) Performance. Rendering operations timed so that the frame refresh rate remains constant during pans and zooms.

27 Pad++ File Browser

28 Pad++ File Browser

29 Pad++ File Browser