Metrics for accessibility on the Vamolà project

Silvia MirriLudovico Antonio MuratoriPaola SalomoniMarco RoccettiDepartment of Computer ScienceUniversity of Bologna

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Summary

Accessibility evaluation The Italian law The Vamolà Project

ValidatorMonitor

Metrics for Accessibility Future Works Conclusion

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Accessibility Evaluation

Automated Web accessibility evaluation tools (parsing HTML code)Based on:

WCAG 1.0Section 508

Online, offlineFreeware, shareware

Manual testsTests 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 508XHTML 1.0 Strict DTD At least 0.5 em between a link and the following

one ...

It bounds every public institutionautomatic check procedures subjective, manual evaluation by accredited

experts

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The Vamolà Project

A collaboration between the University of Bologna and the Emilia Romagna Region

2 applications:An automatic validatorA monitor

Goals:aiding public institution to survey their Web sites

getting together all the automatic proceduresproviding guidelines to the subjective manual

evaluations

pointing out a portrait of accessibility and its dynamics in time

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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 servicea module for the Apache Web server

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The Validator

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The Validator

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The Monitor

Web-centered application:Stores characteristics of evaluated Web sites

(geographical location, administrative role, …)Allows authorized users to choose:

Time periodDepth 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 resultsProvides some in-time reports, Web sites

improvements, etcShows its results on an SVG map and on a HTML

table

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The Monitor

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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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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 criteriaChecks

related to each of the 22 requirementsrelated to aspects which involved particular groups of

users

Web sitesInstitution domain (geographically or administratively)Size (number of pages) Services provided (as forms, multimedia object, etc)

Parameters of each metrics

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Our metrics

Collaborative communitiesdifferent 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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Conclusion

At the present time Vamolà is an ongoing project:We are designing and developing the

prototype of the validatorWe 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