Application of the Strain Index in multiple task jobs.
Bao-S; Spielholz-P; Howard-N; Silverstein-B
Appl Ergon 2009 Jan; 40(1):56-68
Six different methods to calculate the Strain Index (SI) scores for jobs with multiple forces/tasks were developed. Exposure data of 733 subjects from 12 different worksites were used to calculate these SI scores. Results show that using different SI computation methods could result in different SI scores, hence different risk level classifications. However, some simpler methods generated SI scores were comparable to the more complicated composite SI method. Despite differences in the scores between the six different SI computation methods, Spearman rank-order correlation coefficients of 0.61-0.97 were found between the methods. With some confidence, ergonomic practitioners may use simpler methods, depending on their specificity requirement in job evaluations and available resources. Some SI computation methods may tend to over-estimate job risk levels, while others may tend to under-estimate job risk levels, due to different ways used in obtaining the various SI parameters and computations.
Mathematical-models; Risk-analysis; Job-stress; Safety-practices; Workplace-studies; Work-environment; Stress;
Author Keywords: Upper arm musculoskeletal disorders; Exposure quantification; Job evaluation
Stephen Bao, Safety and Health Assessment and Research for Prevention (SHARP) Program, Washington State Department of Labor and Industries, P.O. Box 44330, Olympia, WA 98504
Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
Washington State Department of Labor and Industries