A User-Oriented Evaluation of a Time-Shared Computer System

Criteria for the evaluation of computer systems are traditionally computer science oriented. This exploratory investigation is concerned with evaluations of users´ satisfaction with a time-shared computer system. The first part of the investigation is an experiment indicating that the type of programming language, i.e., Basic versus Fortran, is the relevant significant factor in determining the learning rates for the use of the system. The second part of the investigation is devoted to the study of an additive users´ utility function. The variables of this function are the waiting time in the queue for a time-shared computer terminal and the users´ problem solving time (users´ turnaround time at the terminal). It was found that users became rapidly dissatisfied if these times exceeded 10-15 min. A probability density function for the users´ turnaround time at the terminal was obtained in the setting of an industrial laboratory. It turned out to be nearly exponential with a mean of about 12 min.