1 cs 430 / info 430 information retrieval lecture 15 usability 3
Post on 19-Dec-2015
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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 email the grades and comments this afternoon.
Assignment 3
Due: Monday November 8The assignment will be posted within the next few days
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Course Administration
Seminar next Tuesday
Amit Singhal, GoogleHollister 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
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Browsing in Information Space
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Starting point
Effectiveness depends on
(a) Starting point
(b) Effective feedback
(c) Convenience
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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 performanceno administrative delays (authentication)
Human skills and knowledge augment and extend the automatic methods of searching
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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
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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.
http://www.yahoo.com/
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Browsing the Content of Indexes
Show the users the terms that occur in indexes, such as subject headings.
Example: Library of Congress:American Memory
http://memory.loc.gov/
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QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Subject headings used in index
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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
http://cmi.rlg.org/
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QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Sort "date"
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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.
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QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Alphabetic list
http://nsdl.org/
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QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Graphical display http://nsdl.org/
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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
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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.
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