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Perception of Content, Structure, and Presentation Changes in Web-based Hypertext
Luis Francisco-Revilla Frank M. Shipman III
Richard Furuta Unmil Karadkar
Avital Arora
Center for the Study of Digital Libraries Texas A&M University
What is this talk about?
When dealing with Web-based hypertext, due to its fluid nature, it is continuously required to locate and identify meaningful changes
… but what changes do people find meaningful?We conducted a study to observer how type and
magnitude affected the human perception and assessment of changes on Web pages
…how to use this observations in systems that can aid people?
We created the Walden’s Paths Path Manager that attempts to use this knowledge in order to assess the relevance of the changes
This is a problem everybody has:
Bookmark lists Yahoo! catalogues Meta-document applications such as
Walden’s Paths
Managing Walden’s Paths collection
Paths are meta-documents Sequential arrangement of Web pages Rhetorically coherent Contextualized Distributed ownership Distributed authorship
Continuous revision of the collection
Mechanisms for addressing the issue
Caching the pages Caching strategies (CiteSeer, AltaVista) Some changes are desirable (CNN, Weather)
Fluid paths Ephemeral paths Rhetorical coherence
The real issue
Mechanisms only allowed limited reaction to changes
Detecting changes is easy but determining the relevance is difficult
Humans are still required to determine the significance of changes
In order to react to changes the assessment of their relevance is required
The perception of change
Observe how humans perceive changes of Web pages
Inform and evaluate the approach and design Questions
1. Do people view the same changes in a different way when given different amounts of time?
2. What kind of changes are easily perceived?
3. Of what kind of changes do users want to be notified?
Kinds of change
Content changes (what) Presentation changes (how) Structural changes (linking) Behavioral changes (dynamic)
The participants
18 adults Mostly Texas A&M students Ranging from humanities to sciences Levels from undergraduate to post doctoral
Divided into group A and group B
The study
Participants acted as Information Facilitator in a K-12 school. Their responsibility was to check the Web pages used by other teachers and notify them whenever important changes occurred.
Participants were presented with two version of a Web page in two adjacent monitors
Participants were asked to evaluate the change magnitude and their relevance
The source materials
Mostly selected out of existing paths A modified version was created to reflect a
single type of change
Methodology
Familiarization with testing software and definitions of change
Pre-evaluation questionnaire Phase I (8 pages @ 60 sec/page) Phase II (31 pages @ 15 sec/page) Phase II (31 pages @ 60 sec/page) Post-evaluation questionnaire
Questions
1. From the Content perspective, the degree of change is:
2. From the Structure perspective, the degree of change is:
3. From the Presentation perspective, the degree of change is:
4. Overall, how significant are the changes?
5. If this page were in my bookmark list, I would like to be notified when changes like these occur
Questions 1-4 were answered in a 7-point scale ranging from “none” to “moderate” to “drastic”
Question 5 was answered in a 7- point scale ranging from “strongly disagree” to “strongly agree”
Results: phase I
Results: content and structure
Results: presentation
Implications
Presentation changes were usually perceived as irrelevant
The desire of notification and the perception of overall change increased as the degree of content change did
Time played a larger role for the perception of structural changes than for the content changes
As the degree of structural change increased, so did the desire of notification
Links are useful metrics
Path Manager: the system
Java based Paths or bookmark lists HTML pages Functional state of the document
Original Valid Last-time
Algorithms
Variation of Johnson Weighted sum of
additions, deletions and modifications for each metric
Added metric for structure changes
Flexible Asymmetric Lack normalization
Proportional Determines the
proportion of modification for each metric
Simple Symmetrical Normalized
Initial interface
Overall change relevance assessment
Document signatures
Paragraph checksums Headlines Links Keywords Global checksum
View of change metrics
Detailed view of page metrics
Path information
Web page retrieval and connectivity
Potentially slow and unpredictable Parallel retrieval
Multi-threaded Multiple attempts and retries Different states
Connection state Retrieval state Analysis state
Future Work
Evaluate alternative metrics and algorithms
Evaluate the Path Manager with different collections
Conclusions
The study help to understand what people consider relevant changes
The study revealed that structural changes should be included in the determination of change relevance
The study also show that content changes are highly related to overall magnitude and relevance
The results obtained help to guide the design of the Path Manager
Contact information
Luis [email protected]
Frank M. Shipman, [email protected]
Richard [email protected]
Unmil [email protected]
Avital [email protected]
