Detecting, Assessing and Monitoring Relevant Topics in Virtual Information Environments

Intelligent Database Systems Lab

國立雲林科技大學National Yunlin University of Science and Technology

Detecting, Assessing and Monitoring Relevant Topics in Virtual Information Environments

Jo¨ rg Ontrup, Helge Ritter, So¨ ren W. Scholz, and Ralf Wagner

TKDE, Vol.21, No. 3, 2009, pp. 415-427.

Presenter : Wei-Shen Tai

2009/4/8

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Outline Introduction Managerial information seeking Methods

Hierarchically growing hyperbolic self-organizing maps Information foraging theory Assessment of association rules and statistical testing for changes

Performance evaluation Usability evaluation Discussion and conclusions Comments

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Motivation Environmental Scanning (ES) activities are hampered by an information

overload It caused by the dramatic increase of relevant documents and messages

emitted. Managers need efficient ways to understand their business environment as

well as to integrate this understanding into their planning and decision-making processes.

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Objective

Automated ES systems Supports the limited information processing capacity of humans. Facilitates sensitive and context dependent reductions of the

information overload.

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Managerial information seeking

Situation awareness A manager identifies a topic relevant to his or her business

decisions, he or she is interested in precise information and, particularly, in changes of the relations of facts.

Application domain Example of 2,314 documents obtained from the Internet-

based hospitality industry newsletter, ehotelier.com.

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Hierarchically growing hyperbolic SOM

Hierarchically Growing Hyperbolic SOM (H2SOM) Node’s quantization error QE as the growth criterion. If a

given threshold QE for a node is exceeded, that node is expanded.

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Hierarchical Document Organization

Labeling Terms correspond to the maximal values in the prototype vectors.

Interactive message level display Each node represents a subset of messages, which can be displayed via

“drill down “.

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Topic Detection in Document Streams

Time-dependent activation potential

A distinct peak dominates the message landscape.

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Information foraging theory (IFT)

Information scent

ghi is appraised by means of its relevance in the actual context. Ak is the relevance of a term k via Bayesian prediction.

Information diet

B is total time spent on searching this information, T is the total time spent on extracting and handling the relevant information.

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Assessment of association rules andstatistical testing for changes

Lift and interestingness

Statistical testing with the measures of interestingness For rule 1 (hotel chain reports), χ 2(A →C)=11.82. In contrast, for rule 2

(Bali attacks), χ 2(A →C)= 53.10, and for rule 3 (Iraq war), χ 2(A →C)= 65.63.

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Performance evaluation

Fast tree search capability of the H2SOM

Usability evaluation The degree of completion of both tasks is equal or significantly

lower for subjects using the standard tree browser.

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Discussion and conclusions

An intelligent system for supporting ES process Discovery of new information

H2SOM and an interactive visual exploration. Expansion of knowledge

IFT to digest relevant information sources. Monitoring of already identified topics

More precise assessment of changes in the document stream.

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Comments Advantage

This hybrid intelligent system provides an interactive information exploration tool via visual interface.

It can be integrated into discovery, expansion, and monitoring concepts in cognitive phases of ES.

Drawback It lacks of enough persuasiveness to determine the branching factor nb as an

esthetic view. The growth threshold Θ QE was set to zero but limited the expansion of the

network to a depth of five hierarchy levels. Application

Information discovery, organizing and maintenance.

Documents

Detecting, Assessing and Monitoring Relevant Topics in Virtual Information Environments