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Metrics for accessibility on the Vamolà project

Silvia Mirri

Ludovico Antonio MuratoriPaola SalomoniMarco RoccettiDepartment of Computer ScienceUniversity of Bologna

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Summary

� Accessibility evaluation

� The Italian law

� The Vamolà Project

�Validator

�Monitor

� Metrics for Accessibility

� Future Works

� Conclusion

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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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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

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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 service

�a 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 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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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 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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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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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