ABSTRACT
This chapter develops a technique of goals, operators, methods, and selection rules for the methods (GOMS) analysis at the Unit-Task Level, which is appropriate for this stage of system analysis. It examines two very different layout systems: a Manual System, in which the user has to do most of the layout steps explicitly; and an Automatic System, which does many of these steps for the user. The chapter assumes that the layout system will reside on a small, personal computer with limited main memory and a large disk. It focuses on the assumption of the independence of unit tasks. The chapter examines the independence assumption analytically by pushing the Unit-Task-Level analysis to a finer level of detail. Systems in the early, conceptual stages of design can be analyzed at the Unit-Task Level. The unit tasks to be accomplished are enumerated, their frequencies estimated, and the time per unit task determined.
