SIMS 202 Information Organization and Retrieval

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SIMS 202Information Organization and Retrieval

• Prof. Marti Hearst and Prof. Ray Larson
• UC Berkeley SIMS
• Tues/Thurs 930-1100am
• Fall 2000

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Today

• Modern IR textbook topics
• The Information Seeking Process

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Information Retrieval (IR)

• Information
• Representation
• Storage
• Organization
• Access

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Information vs. Data Retrieval

• IR concerned more with retrieving information
  about a subject than the retrieving data which
  satisfies a given query
• IR usually deals with natural language text which
  is not always well structures and could be
  semantically ambiguous

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Textbook Topics
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More Detailed View
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What Well Cover
A Lot
A Little
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Search and RetrievalOutline of Part I of SIMS 202

• The Search Process
• Information Retrieval Models
• Content Analysis/Zipf Distributions
• Evaluation of IR Systems
• Precision/Recall
• Relevance
• User Studies
• System and Implementation Issues
• Web-Specific Issues
• User Interface Issues
• Special Kinds of Search

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What is an Information Need?
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The Standard Retrieval Interaction Model
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Standard Model

• Assumptions
• Maximizing precision and recall simultaneously
• The information need remains static
• The value is in the resulting document set

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Problem with Standard Model

• Users learn during the search process
• Scanning titles of retrieved documents
• Reading retrieved documents
• Viewing lists of related topics/thesaurus terms
• Navigating hyperlinks
• Some users dont like long disorganized lists of
  documents

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Search is an Iterative Process
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Berry-Picking as an Information Seeking
Strategy (Bates 90)

• Standard IR model
• assumes the information need remains the same
  throughout the search process
• Berry-picking model
• interesting information is scattered like berries
  among bushes
• the query is continually shifting

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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
Q5
Q0
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Berry-picking model (cont.)

• The query is continually shifting
• New information may yield new ideas and new
  directions
• The information need
• is not satisfied by a single, final retrieved set
• is satisfied by a series of selections and bits
  of information found along the way.

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Information Seeking Behavior

• Two parts of a process
• search and retrieval
• analysis and synthesis of search results
• This is a fuzzy area we will look at several
  different working theories.

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Search Tactics and Strategies

• Search Tactics
• Bates 79
• Search Strategies
• Bates 89
• ODay and Jeffries 93

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Tactics vs. Strategies

• Tactic short term goals and maneuvers
• operators, actions
• Strategy overall planning
• link a sequence of operators together to achieve
  some end

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Information Search Tactics (after Bates 79)

• Monitoring tactics
• keep search on track
• Source-level tactics
• navigate to and within sources
• Term and Search Formulation tactics
• designing search formulation
• selection and revision of specific terms within
  search formulation

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Term Tactics

• 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)

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Source-level Tactics

• Bibble
• look for a pre-defined result set
• e.g., a good link page on web
• Survey
• look ahead, review available options
• e.g., dont simply use the first term or first
  source that comes to mind
• Cut
• eliminate large proportion of search domain
• e.g., search on rarest term first

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Source-level Tactics (cont.)

• Stretch
• use source in unintended way
• e.g., use patents to find addresses
• Scaffold
• take an indirect route to goal
• e.g., when looking for references to obscure
  poet, look up contemporaries
• Cleave
• binary search in an ordered file

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Monitoring Tactics(strategy-level)

• Check
• compare original goal with current state
• Weigh
• make a cost/benefit analysis of current or
  anticipated actions
• Pattern
• recognize common strategies
• Correct Errors
• Record
• keep track of (incomplete) paths

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Additional Considerations(Bates 79)

• 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?

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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 (ODay 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.

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Orienteering (ODay 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.

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Orienteering (ODay 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

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Orienteering (ODay 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
• Each stage followed by reading, assimilation, and
  analysis of resulting material

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Orienteering (ODay 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.

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Orienteering (ODay 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

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Stop Conditions (ODay Jeffries 93)

• 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
• Missing information/inferences ok
• business world different than scholarship

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After the Search Analyzing and Synthesizing
Search Results

• Orienteering Post-Search Behaviors
• Read and Annotate
• Analyze 80 fell into six main types

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Post-Search Analysis Types (ODay Jeffries 93)

• Trends
• Comparisons
• Aggregation and Scaling
• Identifying a Critical Subset
• Assessing
• Interpreting
• The rest
• cross-reference
• summarize
• find evocative visualizations
• miscellaneous

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SenseMaking (Russell et al. 93)

• The process of encoding retrieved information to
  answer task-specific questions
• Combine
• internal cognitive resources
• external retrieved resources
• Create a good representation
• an iterative process
• contend with a cost/benefit tradoff

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Sensemaking (Russell et al. 93)

• Most of the effort is in the synthesis of a good
  representation
• covers the data
• increase usability
• decrease cost-of-use

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Summary

• 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
• Sensemaking
• Combining searching with the use of the results
  of search.

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Next Time

• IR Systems Overview
• Query Languages
• Boolean Model
• Boolean Queries