Function refers to an action and is an essential component of any value a business offers to its customers. Irrespective of whether the value is tangible or intangible, it will always include a functional component. The question of how best to describe functionality is an important one in Value Analysis and Value Engineering, and both these fields use a functional definition which calls for expressions describing functionality to comprise a transitive verb and direct object.
In QFD, as well, the practice is to use phrases comprising a verb and object. For example, transmit data, emit a flame, or display images are all typical examples of functional expressions. In these three expressions, the words data, flame, and images are nouns while the words transmit, emit, and display are verbs. Additional words modifying these verbs and nouns can then be used to clarify quality.
When using this kind of functional expression, however, it is often difficult to distinguish the difference between quality and characteristic. For example, when speaking about paper, the expression absorbs water is in the form transitive verb and direct object, and therefore appears to be a functional expression. This phrase can also be interpreted, however, as a description of a physical property of paper. The expression can therefore be understood in either of two ways:
- the product in question utilizes the water-absorbent physical properties of paper or
- the product has the quality of being water absorbent.
In many cases, either interpretation would do, and there are many products that utilize physical properties of the materials from which they are made, which means that deployment of product quality is equivalent to the deployment of the product’s physical properties. And since there are many products that do just that, let us consider any phrase comprising a transitive verb and direct object to be a functional expression.
Another point to be careful of when using a functional expression comprising a transitive verb and direct object is the distinction between autonomous functions and heteronomous functions. An autonomous function is one in which the product is able to affect entirely on its own, whereas a heteronomous function is one affected only by interaction with a human.
For example, let’s look at a simple cigarette lighter. A cigarette lighter performs the autonomous function of storing benzene gas and also performs the heteronomous function of emitting a flame. Anyone who has ever operated a cigarette lighter can understand this example. A lighter placed on the table stores gas but does not emit a flame. Pick the lighter up and operate it, however, and it will emit a flame.
Always keep in mind the difference between autonomous and heteronomous functions when using functional expressions to describe a product because the more autonomous functionality a product has, the fewer humans have to do to operate it. It is necessary to remember the difference between these two types of functionality and how to describe them using functional expressions. Let’s also think about the relationship between functional expressions and quality. One easy-to-understand definition of quality is the extent to which functionality is achieved. The extent to which functionality is achieved can also be thought of as related to words that are used to modify the verbs and nouns comprising functional expressions. For example, the phrase transmit data can be modified to explain both how the data was transmitted and what kind of data it was by adding adverbs and adjectives.
One example might be to use the adverb speedily and the adjective accurate to change the phrase to read: speedily transmit accurate data. Adverbs and adjectives describe attributes of the words they modify and help make quality easy to understand. What the customer seeks in the products he purchases is functionality, and irrespective of whether the product is a tangible or intangible one, there will always be some kind of functionality present. The customer will never be satisfied simply with functionality, however, and using words that describe the level of achievement as a high one helps engender customer satisfaction with the offered product. This kind of relationship is shown in Diagram “Anticipated Needs Analysis Sheet”.
In other words, the customer will not be happy simply with a product that transmits data. Gave him a product that transmits data speedily, however, and he will be happy. And since there are various levels of speed, obviously a product that transmits data in just five minutes will be considered higher quality than one that requires an hour. What is more, a product that can transmit data in just two seconds will be considered higher quality than one that requires five minutes. Viewed in this manner, I think it is easy to understand that quality is related to the level of achievement of functionality.
As explained above, quality can be described using expressions comprising transitive verbs, direct objects, and modifiers. For example, transmit accurate data or speedily transmit data are qualitative expressions. So when we consider the quality of paper as explained with a functional expression, instantaneously absorbs moisture is a qualitative expression, in which the modifier instantaneously expresses the level of quality.