Proving external validity of ergonomics and quality relationship through review of real-world case studies

Abstract

Prior lab experiment and simulated environment ergonomics studies revealed the cause-and-effect relationship between ergonomics and quality with high internal validity. However, the external validity, i.e. the generalisability of this relationship to field settings (manufacturing plants) cannot be ascertained unless field experiment studies are conducted. Therefore, the current study aims to review five field experiment ergonomics studies to strengthen the external validity of this relationship. The studies reviewed include Axelsson (2000. Quality and ergonomics: Towards successful integration. Thesis (PhD). Linköpink University) in an assembly plant, Gonzalez et al. (2003. Ergonomic performance and quality relationship: an empirical evidence case. International Journal of Industrial Ergonomics, 31 (1), 33–40) in metal manufacturing, Yeow and Sen (2003. Quality, productivity, occupational health and safety and cost effectiveness of ergonomic improvements in the test workstations of an electronic factory. International Journal of Industrial Ergonomics, 32 (3), 147–163; 2006. Productivity and quality improvements, revenue increment, and cost reduction in the manual component insertion lines through the application of ergonomics. International Journal of Industrial Ergonomics, 36 (4), 367–377) in printed circuit assembly factories, and Erdinc and Vayvay (2008b. Ergonomics interventions improve quality in manufacturing: a case study. International Journal of Industrial and Systems Engineering, 3 (6), 727–745) in a textile factory. The manufacturing tasks, ergonomics and quality methodologies, ergonomics problems, ergonomics interventions, and quality improvement outcomes were examined. The study found that ergonomics problems, particularly awkward postures, cause human error which results in quality defects. All studies show significant reduction in defects and three studies show financial gains, i.e. savings on rejection costs. This research provides researchers and engineers an insight into why ergonomics problems can lead to poor quality and how to assess such problems and apply ergonomics interventions for higher quality performance in manufacturing.