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Function Analysis: Foundation to Concept Development

By Carlos M. Rodriguez posted 11-13-2023 15:12


Function Analysis: Foundation to Concept Development

Read Time: 5 minutes

The details are details. They make the product. The connections, the connections, the connections. In the end, it will be these details that give the product life.

Charles Eames

Consumers purchase products because they can perform specific functions. For example, a consumer will buy a cellular phone because it accomplishes the “facilitates communication” function. A customer will purchase a lawn mower because it performs the function of “cutting grass.” These are known as the basic functions. Products and services generally perform basic and secondary functions in response to specific customer demands. These secondary functions become the opportunity to differentiate the products and provide the customers with additional value that will favor a particular brand over others in the marketplace—innovation concerns how we select solutions to perform basic and secondary functions.

The basic function of a watch is to provide the time of the day. Secondary functions are alarms, water resistance used in diving, cellular phone capability, and satellite navigation. In addition, watches constitute objects with a representative value that suggests signs associated with work, productivity, enterprise, and success; on the one hand and the other, these values represent status, luxury, and self-indulgence. Function analysis is a technique used to describe a product from a functional perspective and evaluate the interactions among the embedded functions. It aims to represent the physical solution that performs each function and is particularly useful at the design stage when a basic product description is available.

Function Analysis

Every product performs at least one function. A function is a purpose that a thing or activity is intended to perform and is expressed as a pair combination of a “verb” and a “noun,” which is generally referred to as a “function name” or “function statement.” Verbs must be active since a function defines an “action” upon something. For example, a lawn mower functions as a “cut grass.” In this example, the function “cut’ has been defined over the noun “grass” as: “a necessary intent or causal action that is realized through the performance of a solution.” This “solution” is the lawn mower. 

Purpose of Function Names

Thus far, we have learned to define function names. These criteria foster successful product design and manufacture and ultimately determine its performance. Mainly, function names are used to:

  1. Identify specific functions of a product and allow product comparison analysis.
  2. Separate the intent or purpose of a thing from its appearance, thus focusing on product functionality and performance.
  3. Rank functions in order of preference as required by consumers and allow optimal allocation of resources as customer demands are served.
  4. Enable cost reduction approaches by focusing on what the function accomplishes, thus improving value by reducing the cost-function relationship of a product.
  5. Facilitate creativity by visualizing different ways a function can be accomplished.
  6. Allows multidisciplinary teams to communicate using a common language while addressing problems objectively.

Random Function Determination

Random function determination is a technique developed by L.D. Miles that categorizes the types of functions implemented in a product. The method identifies the functions and determines which are basic and secondary. For this, it is essential to adopt a particular “level of abstraction” as the level used to identify functions. If you choose the perspective of the whole product or service, then you focus on identifying the basic function at the highest level of abstraction. However, since a product combines several components, you may select to specify functions at the component level of analysis. When the level of analysis is the whole product, the functions related to components become secondary functions and are related to the basic function.

This technique uses the how-else question when attempting to discover functions at the product or component level. This question reads as: How else can this function be accomplished? The following section provides several examples to illustrate the identification of basic and secondary functions.

Higher and Lower Level Functions

So far, we have listed several functions for a particular problem and determined the basic and secondary functions. In guiding most design efforts, it is critical to establish a hierarchy of such functions. To do this, you start with the list of functions associated with a specific product. If we were to select a particular function from this list and ask: Why do I need to perform this function? The answer will be given by another existing function or a new one to be included. As such, this new function is higher in the hierarchy and initially becomes the “new” basic function. The higher function will be positioned to the left of the initial function, as shown in Figure 1.

Figure 1 - Higher and lower level function determination with the present function as a reference.
Source - Rodriguez, Carlos M. (2016), Product Design and Innovation: Analytics for Decision Making, CreativeSpace Publishing.

Figure 2 illustrates a technical-oriented FAST. This diagram shows the relationship among objectives, actions, and components. The higher-order function represents the “goal” rarely satisfied by the solution to the problem. The basic function should be satisfied by the solution to the problem. The diagram also shows several secondary functions that define the critical path. This diagram follows the how-why logic.

Figure 2 - Technical-oriented FAST diagram

Source: Adapted from Moga, L., Ionita, I., Buhociu, F., Antohi, V. & Virlanuta, F. (2009) Introducing technical oriented fast diagrams in the projecting of the informatics systems for the management of small and medium-sized enterprises. Communications of the IBIMA, 8(65-74). In Rodriguez, Carlos M. (2016), Product Design and Innovation: Analytics for Decision Making, CreativeSpace Publishing.


Carlos Rodriguez

Carlos M Rodriguez is an Associate Professor of Marketing and Quantitative Methods and Director of the Center for the Study of Innovation Management, CSIM in the College of Business, Delaware State University, USA. His publications have appeared in the Journal of Business Research, Journal of Business to Business Marketing, Journal of International Marketing, International Marketing Review, Management Decision, International Journal of Business and Social Sciences, Journal of Business and Leadership, and Journal of Higher Education Research & Development among others and several conference proceedings. Currently, he serves in the editorial board of several journals. His research interests are in the areas of entrepreneurship and strategic capabilities, luxury branding and experiences, product design and new product development teams, and relationship marketing. He recently published the book entitled Product Design and Innovation: Analytics for Decision Making centered in the design techniques and methodologies vital to the product design process. He is engaged in several international educational, research, and academic projects, as well, as, international professional activities.

Further Reading

Bytheway, Charles W. 2007. Fast Creativity & Innovation. Fort Lauderdale, Florida: J. Ross Publishing.

Hundal, M.S. 1990. A Systematic Method for Developing Function Structures, Solutions and Concept Variants. Mechanical Machine Theory 25 (3): 243-256.

Kaufman, J. Jerry, and Roy Woodhead. 2006. Stimulating Innovation in Products and Services. Edited by Andrew P. Sage, Systems Engineering and Management. Hoboken, New Jersey: Wiley.

Suh, Nam P. 1990. The Principles of Design. New York, NY: Oxford University Press.

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