Cost effectiveness of operator features in equipment design

In design negotiation, the attribution of credible values to the incorporation or deletion of operator features allows engineers the freedom to judge the overall effect of human factors recommendations in relation to the achievement of a design specification. Likewise in the development phase, product planners frequently need more precise statements about productivity, training needs and general operational performance than, "it will be greater/less, worse/better than...". The method described utilises measured and synthetic data, learning theory and Markov processes to calculate the likelihood of operator task failure. These failure rates are then treated via filter factors derived from the application of the Nominal Groups Technique to give a global statement of the likelihood of operator failure resulting in unscheduled calls for service. Using the relationship between the cost of service calls and the overall life cost of developing, manufacturing, marketing and supporting a leased product, it is then possible to place credible values on the design features in question. Thus during the design process it becomes feasible to calculate the likely effects of human factors recommendations and modifications in relation to manufacturing costs, and thereby facilitate rational assessment of their implementation on a sound economic basis. This technique has been used to considerable effect, and represents a useful additional tool for the human factors practitioner in the design negotiation process. Further developments and refinements are planned, and it is anticipated that a similar technique will shortly be available to enable assessment of the effectiveness of product training programmes and job aids.