ABSTRACT
In ergonomic intervention research, the main purpose is to offer sufficiently valid conclusions about the invention effect under study. A number of different methods have been suggested and used for assessing perceived load, discomfort, and subjective health before and after an intervention, such as direct measurements on site, systematic observations (according to specimen records), and gathering the subjects’ own reports and experiences according to standardized self-report questionnaires. A comparison of these three kinds of methods is offered by Winkel and Mathiassen (1994) concerning aspects as cost, capacity, versatility, generality, and exactness. Standardized self-report measures or questionnaires have advantages compared to the other two in that they allow data to be collected from a large number of people, including versatile information about each of the exposure variables, as well as the exposure in general, but less exact information about the kind and localization of the physical load. Standardized selfreports are most appropriate when used in epidemiological studies, according to these authors. In the comprehensive review of ergonomic intervention research for improved musculoskeletal health (Westgaard and Winkel 1997), a combination of methods is apparent, among them standardized self-report questions or statements with corresponding rating scales. These are used to assess subjective discomfort/ comfort related to the musculoskeletal system or a combination of psychosocial factors (control at work, job involvement, social relations, supervisor/leadership climate) and physical factors (work-environment aspects, physical work load, musculoskeletal symptoms).
