Operational Definition

Operational definition is a term coined by Nobel Prize winning physicist Percy Bridgeman roughly 70 years ago. It is still not widely known or understood, yet it provides a backbone for understanding processes that is more powerful than almost any other factor.

Operational definitions have been called, “…definitions you can do business with…” Let us, for the sake of discussion, examine an operating instruction that says, before beginning the procedure, the table must be dry. That begs the question of what we mean when we say dry. The concept of ‘dryness’ is ephemeral. For the purposes of following the procedure, it must be defined. In and of itself to say, “the table must be dry”, means nothing. How dry? Very dry? Extremely dry? You see, more adverbs don’t help, we still have to say what dry means.

The definition will depend on the purpose. For example, in a restaurant one may say that “before setting the table, the busboy should make sure that it’s dry”. In this case ‘dry’ probably means no visible moisture. In the another business heating may be required to achieve the required level of dryness. How dry is defined depends on situation. The same is true for clean, safe, sterile, fast, religious, fit, very fit, alert and even logical. In order to be useful for measurement these terms must be defined. Is this table dry (enough)? It must be spelled out. If it is not two parties will disagree because they are using the same term in different ways.

This is particularly important in training. For example an instruction may be to fill the sink until it is full. What does this mean? How full is full? More importantly how would a person trying to do this job know when he or she had done it? People will guess. They won’t tell you they are guessing, but that is what will happen and two different people will arrive at two different definitions of when that job is done. Perhaps now one can begin to see the pervasive need for operational defintions. And, we have yet to even leave the workplace. What about customer and supplier. The customer says that on arrival the purchased goods must be clean. What does that mean? No visible soiling? Clean to the naked eye or clean at 100x? In order to be called a cotton shirt, the fabric can have no less than 90% cotton. What does this mean. Does it mean 100% cotton except for the collar? What does it mean to say a bill must be paid on time?

If we want to study the impact of various sales terms (e.g. Net Due, 1, 10% Net 30) on Whether or not bills are paid on time, we must have the same definition of ‘on time’ for comparison of the various sales terms. Otherwise differences that may appear to be due to the different sales terms could, in fact, be the function of differing definitions of ‘on time’.

Is this lack of operational defintions a problem? Without doubt it is and it is everywhere. As Deming used to say, “People on the job that don’t know what the job is.” If management is prediction and the enemy of prediction is variation then we have within our grasp a method of reducing variation and improving prediction simply by taking the time to operationally define our key concepts.