Usability Evaluation Factors  for Measuring an Accessible Mobile E-Book Applications for Visually Impaired

The emergence of e-books opens new opportunities for the visually impaired to overcome reading struggling. However, current mobile e-book applications are still not reaching their satisfactory level because of the limitations of mobile devices and lack of understanding of visually impaired needs among mobile application developers. Besides, important factors involve in usability evaluation studies for these applications are still unclear. Therefore, this study aims to develop a usability evaluation model to evaluate an accessible mobile e-book application for the visually impaired. Hence, the study conducted a literature review to identify the usability factors. Secondly, identify the factors that are most frequently used. The authors summarised the identified factors to develop the most important factors relevant to e-book applications for the visually impaired. Thirdly, these factors were then verified by eleven experts. In total, 36 factors were identified from the first phase. The study proposed only five factors: efficiency, effectiveness, satisfaction, learnability, and visual impaired accessibility after applying the summarization and simplifying methods. The results from the expert review shows that all experts agreed with the proposed factors as all the factors get a high average of at least four out of five. These identified factors are vitally important elements to be considered by mobile e-book developers and designers in evaluating whether their mobile e-book applications are usable and accessible to the visually impaired. Consequently, the visually impaired users of mobile e-book application will have the same chance as sighted to benefits from e-book applications.