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
Modern IR textbook topics
 The Information Seeking Process
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Textbook Topics
More Detailed View
What We’ll Cover
A Lot
A Little
Search and Retrieval
Outline of Part I of SIMS 202
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The Search Process
Information Retrieval Models
Content Analysis/Zipf Distributions
Evaluation of IR Systems
– Precision/Recall
– Relevance
– User Studies
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System and Implementation Issues
Web-Specific Issues
User Interface Issues
Special Kinds of Search
What is an Information Need?
The Standard Retrieval
Interaction Model
Standard Model
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Assumptions:
– Maximizing precision and recall
simultaneously
– The information need remains static
– The value is in the resulting document
set
Problem with Standard Model:
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Users learn during the search
process:
– Scanning titles of retrieved documents
– Reading retrieved documents
– Viewing lists of related topics/thesaurus
terms
– Navigating hyperlinks
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Some users don’t like long
disorganized lists of documents
Search is an Iterative Process
Repositories
Goals
Workspace
“Berry-Picking” as an Information
Seeking Strategy (Bates 90)
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Standard IR model
– assumes the information need remains
the same throughout the search process
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Berry-picking model
– interesting information is scattered like
berries among bushes
– the query is continually shifting
A sketch of a searcher… “moving through many
actions towards a general goal of satisfactory
completion of research related to an information
need.” (after Bates 89)
Q2
Q4
Q3
Q1
Q0
Q5
Berry-picking model (cont.)
The query is continually shifting
 New information may yield new ideas
and new directions
 The information need
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– is not satisfied by a single, final
retrieved set
– is satisfied by a series of selections and
bits of information found along the way.
Information Seeking Behavior
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Two parts of a process:
» search and retrieval
» analysis and synthesis of search results
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This is a fuzzy area; we will look at
several different working theories.
Search Tactics and Strategies
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Search Tactics
– Bates 79
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Search Strategies
– Bates 89
– O’Day and Jeffries 93
Tactics vs. Strategies
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Tactic: short term goals and
maneuvers
– operators, actions
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Strategy: overall planning
– link a sequence of operators together to
achieve some end
Information Search Tactics
(after Bates 79)
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Monitoring tactics
– keep search on track
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Source-level tactics
– navigate to and within sources
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Term and Search Formulation tactics
– designing search formulation
– selection and revision of specific terms within
search formulation
Term Tactics
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Move around the thesaurus
– superordinate, subordinate, coordinate
– neighbor (semantic or alphabetic)
– trace -- pull out terms from information
already seen as part of search (titles,
etc)
– morphological and other spelling variants
– antonyms (contrary)
Source-level Tactics
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“Bibble”:
– look for a pre-defined result set
– e.g., a good link page on web
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Survey:
– look ahead, review available options
– e.g., don’t simply use the first term or first
source that comes to mind
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Cut:
– eliminate large proportion of search domain
– e.g., search on rarest term first
Source-level Tactics (cont.)
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Stretch
– use source in unintended way
– e.g., use patents to find addresses
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Scaffold
– take an indirect route to goal
– e.g., when looking for references to obscure
poet, look up contemporaries
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Cleave
– binary search in an ordered file
Monitoring Tactics
(strategy-level)
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Check
– compare original goal with current state
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Weigh
– make a cost/benefit analysis of current or
anticipated actions
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Pattern
– recognize common strategies
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Correct Errors
Record
– keep track of (incomplete) paths
Additional Considerations
(Bates 79)
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Add a Sort tactic!
More detail is needed about short-term
cost/benefit decision rule strategies
When to stop?
– How to judge when enough information has been
gathered?
– How to decide when to give up an unsuccesful
search?
– When to stop searching in one source and move
to another?
Lexis-Nexis Interface
What tactics did you use?
 What strategies did you use?
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Implications
Interfaces should make it easy to
store intermediate results
 Interfaces should make it easy to
follow trails with unanticipated
results
 Makes evaluation more difficult.
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Orienteering
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(O’Day & Jeffries 93)
Interconnected but diverse searches on a
single, problem-based theme
Focus on information delivery rather than
search performance
Classifications resulting from an extended
observational study:
– 15 clients of professional intermediaries
– financial analyst, venture capitalist, product
marketing engineer, statistician, etc.
Orienteering
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(O’Day & Jeffries 93)
Identified three main search types:
– Monitoring
– Following a plan
– Exploratory
A series of interconnected but diverse
searches on one problem-based theme
– Changes in direction caused by “triggers”
Each stage followed by reading,
assimilation, and analysis of resulting
material.
Orienteering
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(O’Day & Jeffries 93)
Defined three main search types
– monitoring
» a well-known topic over time
» e.g., research four competitors every quarter
– following a plan
» a typical approach to the task at hand
» e.g., improve business process X
– exploratory
» explore topic in an undirected fashion
» get to know an unfamiliar industry
Orienteering
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(O’Day & Jeffries 93)
Trends:
– A series of interconnected but diverse
searches on one problem-based theme
– This happened in all three search modes
– Each analyst did at least two search types
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Each stage followed by reading,
assimilation, and analysis of resulting
material
Orienteering
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(O’Day & Jeffries 93)
*Searches tended to trigger new directions
– Overview, then detail, repeat
– Information need shifted between search
requests
– Context of problem and previous searches were
carried to next stage of search
*The value was contained in the accumulation of
search results, not the final result set
– *These observations verified Bates’ predictions.
Orienteering
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(O’Day & Jeffries 93)
Triggers: motivation to switch from one
strategy to another
– next logical step in a plan
– encountering something interesting
– explaining change
– finding missing pieces
Stop Conditions
(O’Day & Jeffries 93)
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Stopping conditions not as clear as for
triggers
People stopped searching when
– no more compelling triggers
– finished an appropriate amount of searching for
the task
– specific inhibiting factor
» e.g., learning market was too small
– lack of increasing returns
» 80/20 rule
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Missing information/inferences ok
– business world different than scholarship
After the Search:
Analyzing and Synthesizing Search
Results
Orienteering Post-Search Behaviors:
– Read and Annotate
– Analyze: 80% fell into six main types
Post-Search Analysis Types
(O’Day & Jeffries 93)
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Trends
Comparisons
Aggregation and Scaling
Identifying a Critical Subset
Assessing
Interpreting
The rest:
» cross-reference
» summarize
» find evocative visualizations
» miscellaneous
SenseMaking (Russell et al. 93)
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The process of encoding retrieved
information to answer task-specific
questions
Combine
– internal cognitive resources
– external retrieved resources
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Create a good representation
– an iterative process
– contend with a cost/benefit tradoff
Sensemaking (Russell et al. 93)
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Most of the effort is in the synthesis
of a good representation
– covers the data
– increase usability
– decrease cost-of-use
Summary
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The information access process
– Berry picking/orienteering offer an
alternative to the standard IR model
– More difficult to assess results
– Interactive search behavior can be
analyzed in terms of tactics and
strategies
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Sensemaking:
– Combining searching with the use of the
results of search.
Next Time
IR Systems Overview
 Query Languages
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– Boolean Model
– Boolean Queries