1. 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

2. 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

3. This is a problem everybody has: Bookmark lists Yahoo! catalogues Meta-document applications such as Walden’s Paths

4. 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

5. Mechanisms for addressing the issue Caching the pages Caching strategies (CiteSeer, AltaVista) Some changes are desirable (CNN, Weather) Fluid paths Ephemeral paths Rhetorical coherence

6. 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

7. 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?

8. Kinds of change Content changes (what) Presentation changes (how) Structural changes (linking) Behavioral changes (dynamic)

9. 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

10. 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

11. The source materials Mostly selected out of existing paths A modified version was created to reflect a single type of change

12. 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

13. 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”

14. Results: phase I

15. Results: content and structure

16. Results: presentation

17. 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

18. Path Manager: the system Java based Paths or bookmark lists HTML pages Functional state of the document Original Valid Last-time

19. 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

20. Initial interface

21. Overall change relevance assessment

22. Document signatures Paragraph checksums Headlines Links Keywords Global checksum

23. View of change metrics

24. Detailed view of page metrics

25. Path information

26. 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

27. Future Work Evaluate alternative metrics and algorithms Evaluate the Path Manager with different collections

28. 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

29. Contact information Luis Francisco-Revilla l0f0954@csdl.tamu.edu Frank M. Shipman, III shipman@csdl.tamu.edu Richard Furuta furuta@csdl.tamu.edu Unmil Karadkar unmil@csdl.tamu.edu Avital Arora avital@csdl.tamu.edu