TURF: toward a unified framework of EHR usability.

This paper presents a unified framework of EHR usability, called TURF, which is (1) a theory for describing, explaining, and predicting usability differences; (2) a method for defining, evaluating, and measuring usability objectively; (3) a process for designing built-in good usability; and (4) once fully developed, a potential principle for developing EHR usability guidelines and standards. TURF defines usability as how useful, usable, and satisfying a system is for the intended users to accomplish goals in the work domain by performing certain sequences of tasks. TURF provides a set of measures for each of the useful, usable, and satisfying dimensions of usability. TURF stands for task, user, representation, and function, which are the four components that determine the usability of an EHR system. These four components are described with theoretical descriptions along with examples of how usability is measured in several case studies. How TURF can be used to improve usability through redesign is also demonstrated in a case study. In summary, this paper states that usability can not only be defined scientifically under a coherent, unified framework, it can also be measured objectively and systematically.