Evaluating the usability and usefulness of a digital library

Purpose - System usability and system usefulness are interdependent properties of system interaction, which in combination, determine system satisfaction and usage. Often approached separately, or in the case of digital libraries, often focused upon usability, there is emerging consensus among the research community for their unified treatment and research attention. However, a key challenge is to identify, both respectively and relatively, what to measure and how, compounded by concerns regarding common understanding of usability measures, and associated calls for more valid and complete measures within integrated and comprehensive models. The purpose of this paper is to address this challenge. Design/methodology/approach - Identified key usability and usefulness attributes and associated measures, compiled an integrated measurement framework, identified a suitable methodological approach for application of the framework, and conducted a pilot study on an interactive search system developed by a Health Service as part of their e-library service. Findings - Effectiveness, efficiency, aesthetic appearance, terminology, navigation, and learnability are key attributes of system usability; and relevance, reliability, and currency key attributes of system usefulness. There are shared aspects to several of these attributes, but each is also sufficiently unique to preserve its respective validity. They can be combined as part of a multi-method approach to system evaluation. Research limitations/implications - Pilot study has demonstrated that usability and usefulness can be readily combined, and that questionnaire and observation are valid multi-method approaches, but further research is called for under a variety of conditions, with further combinations of methods, and larger samples. Originality/value - This paper provides an integrated measurement framework, derived from the goal, question, metric paradigm, which provides a relatively comprehensive and representative set of system usability and system usefulness attributes and associated measures, which could be adapted and further refined on a case-by-case basis.