A task-based approach to assessing the accessibility of web sites

Craven, Jenny and Nietzio, Annika (2007) A task-based approach to assessing the accessibility of web sites. Performance measurement and metrics, 8 (2). pp. 98-109. ISSN 1467-8047

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Abstract

Purpose – The purpose of this paper is to describe research undertaken for the European Internet Accessibility Observatory (EIAO) project. It aims to demonstrate how, using a task-based approach, statistical measures can be applied to an initial assessment of a web site's accessibility, which could then be applied to further assessments to provide an evolving picture of the ongoing accessibility of a web site. Design/methodology/approach – Task-based assessments were used to assess the accessibility of web sites, using quantitative and qualitative analysis. The findings from this approach were mapped onto a probabilistic model, developed to assess the probability of an accessibility barrier relating to a specific feature or features of a web site. Findings – The paper finds that providing participants with a task instead of allowing them to randomly explore and evaluate a web site yielded more comparable results. For the EIAO project team, the benefit of the task-based approach was that it allowed them to compare the user testing results with the results of the automated testing tool developed by the project. From the aggregation models included in the analysis, the most appropriate model and parameters were selected, and adjustments were made according to the comparison outcome. Research limitations/implications – Due to resource limitations and efficiency requirements, the assessments undertaken were limited to automatic evaluation, which could also be tested by the users. Therefore not all accessibility barriers in a web site could be identified. Despite this, it is felt that the outcome of the automatic analysis can be utilised as indicator for the overall accessibility of the web site. Originality/value – This paper provides a framework for web designers, commissioners, and policy makers to undertake a user focussed assessment of the accessibility of their web sites, which could be used in conjunction with other assessment methods.