Bias in ergonomic experiments.
In a within-subject experimental design, each person receives a number of conditions in a balanced or random order.. The design produces asymmetrical transfer and range effects. Yet practically all ergonomic recommendations are based upon the results of experiments which use this kind of design. The recommendations need to be checked, using separate groups of people for each experimental condition.
Poulton
E C
EC
Medical Research Council, Applied Psychology Unit, Cambridge.