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Towards a sustainable web accessibility

Cases like Target.com show that there is still uncertainty about the precise meaning of “web accessibility”, about how to identify accessibility problems, and about when to claim that a web site is accessible. In this paper I suggest that the only way to change this is by focussing on sustainable accessibility, i.e. by shaping and establishing effective accessibility processes that can be sustained mainly by their own return on investment and by minimal additional resources. To achieve a sustainable accessibility, at least two issues need to be addressed. First, accessibility evaluations have to produce sets of accessibility problems that are prioritized by their impact: in other words, evaluations should identify problems whose solution makes a big difference in accessibility. Therefore, evaluators and developers can focus on these problems first, thus optimizing their resources. Secondly, accessibility processes (involved when conceiving, developing, maintaining, revamping web sites) should be effective and efficient. After discussing the role that a well defined accessibility model plays, the paper illustrates recent findings concerning quality factors of each type of accessibility process, including: sensitivity, correctness, specificity and reliability of elicitation processes; reliability and validity of processes for sampling pages/resources of a website and of accessibility measurement processes. Several of these factors were experimentally studied in recent and still ongoing experiments, and the paper discusses the overall conclusions.