The measurement of psychological characteristics

Abstract

It is not totally unknown for an occupational therapist to feel the need to assess, say, memory in a patient and to ‘make up’ a test. A case in point would be when a number of items are presented to a patient on a tray for a few moments; the tray is then taken away, and the patient is asked to name as many items as possible. This is not a valid procedure. Such ‘tests’ should never be used unless the aim is solely to obtain a very general notion of what the person can do at that point in time. To be a proper test you need to know, for example, what scores people of a comparable age, intelligence and culture would obtain; and whether you are actually measuring a person’s memory and not anxiety or something else. You also need to know if the same individual would get the same score on two separate occasions. You will also have to ensure that the items are shown for precisely the same amount of time, and that the people are given precisely the same instructions and so on. The standardization of a test, and demonstrations of its reliability and validity, are complex and time-consuming matters.