perception of content, structure, and presentation changes in web-based hypertext luis...

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 Francisco-Revillal0f0954@csdl.tamu.edu

Frank M. Shipman, IIIshipman@csdl.tamu.edu

Richard Furutafuruta@csdl.tamu.edu

Unmil Karadkarunmil@csdl.tamu.edu

Avital Aroraavital@csdl.tamu.edu