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CS 430 / INFO 430 Information Retrieval

Lecture 15

Usability 3

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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:The Human in the Loop

Search index

Return hits

Browse repository

Return objects

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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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Browse: Catalog Record

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Hierarchical browsing

Level 2

Level 1

Level 0

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The Yahoo Interface

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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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Broad categories

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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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Browse everything

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Filter "New York"

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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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Alphabetic list

http://nsdl.org/

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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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Pad++ File Browser

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Pad++ File Browser

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Pad++ File Browser