Task Analysis and the Design of Functionality

this article is that the successful design of functionality requires a task analysis early enough in the system design to enable the developers to create a system that effectively supports the user's task. Thus the proper goal of the design of functionality is to choose functions that are both useful in the user's task, and which together with a good user interface, results in a system that is usable, being easy to learn and easy to use. The user's task is not just to interact with the computer, but to get a job done. Thus understanding the user's task involves understanding the user's task domain and the user's larger job goals. Many systems are designed for ordinary people, who presumably lack specialized knowledge, and so the designers might believe that they understand the user's task adequately well without any further consideration. This belief is often not correct; the tasks of even ordinary people are often poorly understood by developers. But in contrast, many economically significant systems are intended for expert users, and understanding their tasks is absolutely critical. For example, a system to assist a petroleum geologist must be based on an understanding of the knowledge and goals of the petroleum geologist. To be useful, such a system will require functions that produce information useful for the geologist; to be usable, the system will have to provide these functions in a way that the frequent and most important activities of the geologist are well supported. Thus, for success, the developer must design not just the user interface, but also the functionality behind the interface. The purpose of this article is to provide some background and beginning "how to" information on how to conduct a task analysis and how to approach the design of functionality..