Function Analysis

from the Perspective of Competitive Advantage

Edwin B. Dean


[NASA Logo] Function analysis as used here is the process of analyzing the functional, rather than the physical, characteristics of a system. A function may be stated in the form {verb,noun}. It is an action upon something. Eat food, go to work, and cash paycheck are very important functions in the life of most of us.

Akiyama (1991) notes that

Goods and services have various actions. The aim of function analysis is to reveal each of these actions and thus identify the nature of the products and services to which they belong. All products and services are endowed by their creators with certain purposes. Function analysis reveals the intentions or purposes behind the creation of a product or service and thereby identifies the nature of that product or service. Although products and services exist as physical objects or systems, they are not created out of nothing. They are preceded by an idea - a concept - which is the basis of their creation. Function analysis identifies the nature of products and services by revealing these concepts.
Having determined the nature of an object, one can then conceptualize many physical realizations which serve the purpose and choose the realization with the best value. In this manner breakthroughs are designed.

Functional decomposition is the process of asking "how" for each higher level function to derive lower level functions. Functional composition is the process of asking "why" for each lower level function to derive higher level functions. The result is a tree or systematic diagram of functions which fall under some ultimate top level function.

For management, the top level function of the heirarchy of organization functions is the mission (purpose) of the organization. The next lower level functions are things the organization must do (means) to accomplish the mission. For systems engineering and software engineering, the top level function of the heirarchy of product functions is the purpose of the system. The lower level functions are the means to accomplish the purpose. For a multidisciplinary group, the language of what the system must do is independent of the languages of the disciplines, but is common to all. Thus, functional language should be a language of choice for multidisciplinary communication.

Function analysis is also a primary tool for quality function deployment, requirements engineering, and value engineering. Function analysis is the basis for the genopersistation recursion.

Creasy (1973) provides examples of function analysis in the form of Functional Analysis System Technique (FAST) diagrams which are applied both to products and processes.





Function Analysis Bibliography


Surfing the Web

Functional Design


Table of Contents | System Technologies | Use