Dec 2003, DRTC ©C.Watters1

Mobile Access to the Digital Library

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Framework

Save the time of the reader.

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Vision Characteristics of using small devices Migration Models Studies Conclusions

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Vision

user

Digital library

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Characteristics of Using Small Devices

Reading Navigating Task Input Distraction

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Reading

Reading speed Reading comprehension Content Fidelity

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Navigation

Scrolling Lists Hierarchies Hyperspace Context Mental model

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Task and Structure

Task– Simple– Complex

Structure– Text– Lists– Tables

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Input

Stylus Size of targets Speed Accuracy

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Distractions

Noise Lighting Steadiness Battery Time Signal strength

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Automatic Transformations

Why?

How?

Results?

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Scenarios

Full DL access on range of devices

Migration between devices mid-task

Collaboration including mixed devices

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The Problem

Accessing data on a small screen is NOT the same as on a larger screen

Same data for all users

Device display and input get in the way!

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General Approach

Elide Transform

Syntactic

Semantic

Outlining

Remove content

Compress images

Text summarization

Retain*

Full Images

Text/Tables/Forms

Bickmore-Schilit Matrix

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Process

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Decomposition/Parsing

HTML/XML tag clues Structural clues metadata + rules

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Transformations

Text Lists Tables Forms Images Links

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Use Features

In screens, size matters Small screen is NOT just a small window on a

large screen Small screens do work

Scrolling minimized Context preserved Search added Hierarchy used

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Text Transformations

Chunk text to logical units Eliminate sideways scroll Keep clear context Add search

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Text

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Lists

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Forms

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Transformation

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90% effective over 200 random sites with forms

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Problems

Tables used as display structures Long segments Maps and images within form

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Tables & forms

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Tables

Using complete large tables on small devices

Does it pay to: Use screen space for headings and context Use screen space for a search function

For: Simple look up task More complicated task

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Tables

Tables

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Results:Effectiveness

Both tasks did better on whole table For simple task bigger screen significantly better For complex task no significant difference by size For complex task adding context gave significant

improvement

search caused wrong answers in complex task and more so as the screen got smaller

[got to the wrong place faster or just wanted to use it ‘cause it was there!]

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Results

Size matters for both efficiency and effectiveness

Context is worth the space

Search function is not necessarily helpful for complex task for table data– Make it optional/toggable

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Collaborative sessions

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Large screen view

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Device independence

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Small screen view

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Transformation Models

Direct Linear Focus + Context

– DNA Maps– Gateways

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Mapping Options

hierarchy

sequence

type

Focus + context

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Transformations

Patterns of transformations Studies

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Direct

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Linear

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Linear/Hierarchical

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Summaries

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Focus + Context

Late Committal Navigation– Do not click thru the hierarchy but go directly– Extract enough info to decide– Brush through hierarchy or list of segments

Presence of an overview

Continuity of mental model

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Brush Navigation

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Gateway

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25 site study

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Comparative Task Completion Use one small screen version to find one story

Gateway Linear Direct Migration

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Study Conclusions

Users prefer gateway and direct when they have used the site previously

Mental model is important to the user Users performed reading and lookup tasks

best on the gateway version

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Summary of Findings

Size matters Stability in mental model matters Images and style matter Input matters Bandwidth matters

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Summary

Understand ramifications of size on value of experience for the user

Minimize cognitive overhead of the user DL’s should be accessible on mobile devices

Save the time of the reader

Dec 2003, DRTC©C.Watters53

Thank You!

www.cs.dal.ca/~watters

Or the Web Information Filtering Lab

www.cs.dal.ca/wifl