Usability evaluation of universal user interfaces with the computer-aided evaluation tool PROKUS

The rapid dissemination of computer systems and accessible information systems (e.g. internet) is still unbroken. On the individual level, human-computer interfaces and dialogues change many people's lives: examples are the daily work at visual display terminals, digital lectures on the web and home working software tools. A few years ago, it was unusual to assess and evaluate such software or interfaces. Nowadays, researchers and practitioners are recognising the problems which grow up when usability evaluations are neglected. Usability evaluations can be carried out in different phases at the software lifecycle. It requires appropriate procedures with various techniques and methods to request and scope these different occasions. For the purpose of systematic usability evaluation, the ifab-Institute of Human and Industrial Engineering of the University of Karlsruhe (Germany) has developed an evaluation tool called PROKUS (Programmsystem zur kommunikationsergonomischen Untersuchung rechnerunterstutzter Verfahren). This evaluation tool can be used for designing and carrying out usability evaluations in a reproducing and numerical process adapted to different occasions of the software lifecycle. The following paper will describe the evaluation process with PROKUS. Moreover, it will awake special attention to the scientific background of the development and the realisation of the evaluation tool PROKUS. A recently completed evaluation study on universal human-computer interfaces with PROKUS will complete the paper. For illustrating the procedure of PROKUS two web browsers exemplarily tested to what extent it fulfils the required standards of ISO 9241-14, 16 and 17. 1. NECESSITY AND OCCASIONS TO EVALUATE THE USABILITY OF HUMAN-COMPUTER INTERFACES Due to the increasing use of data processing in all fields in human life (e.g. work, education, leisure) the attention given to a universal user-friendly software design is rising. The quality and acceptance of an interactive humancomputer system is highly dependant upon the ergonomic design of the user interface. In the past, ergonomic aspects were often neglected when developing software and information systems. Thus, many users complain about the troubles in learning to use a software product or its insufficient functionality and complexity of interactions. Once the user becomes dissatisfied with a software product, a dialogue system or an accessible interface, this dissatisfaction dominates the functionality and the productivity of the system. A few years ago, it was unusual to assess and evaluate such software or interfaces. Nowadays, researchers and practitioners are recognising the problems which surface when usability evaluations are neglected. Furthermore, the evaluation of accessible interfaces (e.g. web pages) is becoming more and more important. New standards for multimedia interfaces, web pages or further advanced information and data technologies (virtual reality etc.) have to be developed and have to be transferred into the design of these modern human-computer systems. The analysis and evaluation of software products or accessible interfaces, which should examine the adequate transfer of user-friendly standards to the design and development of products, can be realised at several occasions in the software lifecycle (figure 1). The first occasion is during the development process of the product by choosing an adequate human-computer interface. Quality tests assess mainly the functionality of the software. Conformity tests compare the product with the requirements of the standards and evaluate the user-friendliness of interfaces and dialogues. Another occasion, performed by the customer or the future user, is helping to select a suitable product by examining existing products on the market and comparing these products (comparison test). In this product selection process, conformity tests are made to assess the adherence to user-friendly standards. When the software has already been selected, several usability tests with additional goals and needs can be carried out in order to support an eventual redesign phase. customer and/or user view developer view lifecycle of a software product quality test market examination installation use software development market introduction redesign market survey product finding conformity test comparison test usability test