Criteria for Usability of Accessible Web Sites

The application of appropriate web site design and evaluation methods help to ensure more usable and accessible web sites. While in the literature guidelines and evaluation methods for accessibility and usability are given and discussed separately, we aim to identify the relationships between these two concepts, in particular considering usability criteria for accessible web sites. In this work, we propose a set of usability criteria for accessible web sites in order to improve the navigability for special users, i.e. the vision impaired. The identification of the 16 criteria suggested herein was performed through empirical feedback, in which simple hypotheses were formulated, then tested. Subsequently, a systematic method was developed on the basis of the tests, resulting in a classification of the criteria according to usability aspects. The proposed criteria have been applied to an existing public administration web site.