Because of the unique characteristics of the human factors (HF) discipline, its measurement also has special characteristics. To demonstrate this, a number of questions must be answered.

First, what is meant by the term measurement? In its broadest sense, measurement is the application of numerical values to physical and behavioral phenomena. For example, in its basic form, measurement involves being able to say that something has a quality “more than” or “less than” something else. Then attempts must be made to develop numerical values to represent “more” or “less.”