Effect of operator competence on assessment of quality control in manufacturing

Abstract

This paper describes the influence of operator competence on judgement of product quality. Manual repetitive work with short work cycle was studied in a manufacturing company. One goal of the company was that all employees would be able to do most production tasks. Forty-six operators participated in a field study of quality control. Based on how many tasks operators could perform, they were classified as high competence or low competence. Operators inspected 30 items, out of which 6 were of poor quality. In average 38% of the good items were rejected and 10% of the poor items were missed. Signal detection theory was used to compare the sensitivity d′ and the criterion β for high and low competence operators and for departments 1 and 2. High competence operators had greater sensitivity and produced less false alarms and misses than low competence operators. The results are discussed in terms of efficiency of company policies and lack of operator feedback. In addition some tasks were perceived by operators as more prestigious and desirable to perform than others. This bias affects the desirability to learn and perform new tasks, and quality control may suffer. It is important to train and maintain competence in quality control as well as in task performance. The use of high competence operators can improve the quality in manufacturing considerably. Relevance to industry Employees with high competence who managed many production tasks performed significantly better in quality control and judgement of quality than employees who managed only few tasks.