Metrics for accessibility on the Vamolà project, authors: Silvia Mirri, Ludovico Antonio Muratori, Paola Salomoni, Marco Roccetti

1. Metrics for accessibility on the
Vamolà project
Silvia Mirri
Ludovico Antonio Muratori
Paola Salomoni
Marco Roccetti
Department of
Computer Science
University of Bologna
Summary
Accessibility evaluation
The Italian law
The Vamolà Project
Validator
Monitor
Metrics for Accessibility
Future Works
Conclusion
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2. Accessibility Evaluation
Automated Web accessibility evaluation
tools (parsing HTML code)
Based on:
WCAG 1.0
Section 508
Online, offline
Freeware, shareware
Manual tests
Tests with users
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The Stanca Act (2004)
22 mandatory requirements (Web sites)
It restricts the WCAG 1.0 and the U.S.
section 508
XHTML 1.0 Strict DTD
At least 0.5 em between a link and the following
one
...
It bounds every public institution
automatic check procedures
subjective, manual evaluation by accredited
experts
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3. The Vamolà Project
A collaboration between the University of
Bologna and the Emilia Romagna Region
2 applications:
An automatic validator
A monitor
Goals:
aiding public institution to survey their Web sites
getting together all the automatic procedures
providing guidelines to the subjective manual
evaluations
pointing out a portrait of accessibility and its
dynamics in time 5
The Validator
It is organized into 22 requisites to be
satisfied (each single requirement could
be chosen and then check)
It is implemented as a three-version
application:
a Web-centered application (based on
Achecker)
a Web service
a module for the Apache Web server
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4. The Validator
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The Validator
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5. The Monitor
Web-centered application:
Stores characteristics of evaluated Web sites
(geographical location, administrative role, …)
Allows authorized users to choose:
Time period
Depth of the evaluation (only the home page, the whole Web
site, a subset of Web pages, …)
Set of requirements
Subset of inserted Web sites to be evaluated
Is based on the validator results
Provides some in-time reports, Web sites
improvements, etc
Shows its results on an SVG map and on a HTML
table
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The Monitor
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6. The Monitor
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Metrics for Accessibility
Several works in the accessibility field are
related to the definition and the proposal of
quantitative metrics for measuring
accessibility
They are based on WCAG 1.0 checkpoints
They take into account
Automatic and semi-automatic checks (errors
and warnings)
Different groups of people with disabilities
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7. Our aims
Comparing the accessibility among Web
sites
Evaluate Web sites an absolute scale
Evaluate Web sites dynamics in time and
on the territory
Evaluate Web sites according to the users’
expectations and preferences
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Our metrics
Counting errors of each class, assigning them a
proper weight (errors, warnings, … )
Clustering criteria
Checks
related to each of the 22 requirements
related to aspects which involved particular groups of
users
Web sites
Institution domain (geographically or administratively)
Size (number of pages)
Services provided (as forms, multimedia object, etc)
Parameters of each metrics
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8. Our metrics
Collaborative communities
different weight and some particular
aspects could be considered as prior or
secondary and hence defining different
metrics
a sort of “majority report” could be
synthesized as a set of parameters to build
one or more customized metrics
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Future work
A prototype of the monitor is being used to
gauge all the parameters appearing on
measures
Future work will deal with the developing
phase and providing suitable, ad hoc
guidelines, based on shortcomings
clustering and measures values
Overridden enhancement and new metrics
are also expected from a future community
of developers on the monitor
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9. Conclusion
At the present time Vamolà is an ongoing
project:
We are designing and developing the
prototype of the validator
We have implemented a prototype of the
monitor and we are revising it in order to
design the final application. This
application open trends about accessibility
metrics and measures
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Contacts
Thank you for your attention!
For further information:
silvia.mirri@unibo.it
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