W3CWeb Accessibility initiative

WAI: Strategies, guidelines, resources to make the Web accessible to people with disabilities

5 December 2011

WAI R&D Symposia » Metrics Home » Report

Symposium Report Summary

The Research Report on Web Accessibility Metrics note format is a W3C Working Group Note developed by the WAI Reseach and Development Working Group (RDWG). It is available online at www.w3.org/TR/accessibility-metrics-report/


Web accessibility metrics are an invaluable tool for researchers, developers, governmental agencies and end users. Accessibility metrics help to better grasp the accessibility level of websites and are therefore helpful to make decisions based on the scores they produce. Recently, a plethora of metrics have been released; however the validity and reliability of most of these metrics is unknown and those making use of them are taking the risk of using inappropriate metrics. In order to overcome such situation, this note provides a framework that considers validity, reliability, sensitivity, adequacy and complexity as the main qualities that a metric should have.

A symposium was organised to observe how current practice is addressing such qualities. We found that metrics addressing validity issues is scarce although some efforts can be perceived as far as inter tool reliability is concerned. This is something that the research community should be aware of, as we might be making futile efforts by using metrics whose validity and reliability is unknown. The reseach realm is perhaps not mature enough or we do not have the right methods and tools. We therefore try to shed some light on the possible paths that could be taken so that we can reach a maturity point.


M. Vigo, G. Brajnik, J. O Connor, eds. Research Report on Web Accessibility Metrics. W3C WAI Research and Development Working Group (RDWG) Notes. (2012) Available at: www.w3.org/TR/accessibility-metrics-report/

BibTex file

@@editor??author = {Markel Vigo and Giorgio Brajnik and Joshue O Connor},
title = {Research Report on Web Accessibility Metrics},
journal = {W3C Research and Development Working Group (RDWG) Notes},
year = {2012},
month = {May},
url = {http://www.w3.org/TR/accessibility-metrics-report/},