Human Performance Engineering Considerations for Very Large Computer-Based Systems: The End User

Effective Human Performance Engineering for a large-scale, computer-based system involves many complex strategic and tactical decisions regarding the computer system design, the target user's behavior, and the organization/environment. Descriptions of the more important performance considerations are presented. These are based primarily on the experience accrued during the last several years in the building of Bell Laboratories centrally developed computer systems for use by telephone company loop operations personnel in assisting them to do their job. The target population can be broken down into these distinct classes: End Users, Database Maintainers, and the Data System Support Staff. This paper focuses on the End User, and specifically the Bell System Service Representative. Important points include: (i) early emphasis of human performance considerations in the computer system design process can reap valuable benefits; (ii) care must be taken to specify input/output design features which have gone through the human/system engineering step of identifying a favorable payoff versus penalty ratio; and (iii) based on measurement data and user interrogation, computer system availability and transaction failures and response times can seriously damage user performance and system acceptance.