Mirri At W4a2009


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

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Mirri At W4a2009

  1. 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 2 1
  2. 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 3 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 4 2
  3. 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 6 3
  4. 4. The Validator 7 The Validator 8 4
  5. 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 9 The Monitor 10 5
  6. 6. The Monitor 11 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 12 6
  7. 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 13 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 14 7
  8. 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 15 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 16 8
  9. 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 17 Contacts Thank you for your attention! For further information: silvia.mirri@unibo.it 18 9