With increasing traffic density, mainly after the Second World War both in the air and on the ground, concern arose over human error, effort, fatigue, stress, comfort, etc. and the call for measurement was heard everywhere. Ceteris paribus the same happened in industry and the basis for the science of ergonomics was born. A host of research followed, dividing the scientific world in hard-liners with respect to objective measurements and those that felt the need for and saw the value of subjective measurements. Annett analyses this dispute appositely, elaborating on the pros and cons of subjective rating scales. A large number of problems are put in perspective by Annett, among which the almost inherently ordinal character of subjective measurements is perhaps most prominent. In some areas such as traffic and transport research, subjective measures and scales are rather common. It is hard to imagine research in this field without subjective measurement, although its ordinal character might suggest otherwise. Specifically in within-subjects designs, however, the ordinal character is not such a problem as it may seem compared with ratio or interval measures. We do not only want to know whether a newly developed system in a vehicle functions well; if the user does not understand or like it, the system will be ignored, misused, not bought, etc. By means of research with suitable with and without system crossover designs, a fair view on both functional and qualitative aspects can be derived. The predictive validity may not be assured, but the sure pitfall of unsuccessful introduction of newly developed, gleaming but disliked techniques can be avoided. Annett stresses other important limitations, besides the ordinal character and predictive validity, such as timing and/or memory, context and consciousness (e.g. in the case of pleasure or pain). Certainly in an applied field, such as traffic and transport, where the measurements are carried out in dynamic situations under often extremely varying conditions, these limitations have to be seriously taken into account. (Author/publisher)
Abstract