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Inter-rater reliability of the strain index
Edward M Stevens1, Gordon A Vos, John-Paul Stephens
1Saint Martin's College, Department of Mechanical Engineering, Lacey, Washington 98503, USA. ed_stevens_jr@hotmail.com
Journal of Occupational and Environmental Hygiene
|January 28, 2005
Summary
The Strain Index tool shows good inter-rater reliability for hazard classification, crucial for assessing workplace musculoskeletal disorder risk. This indicates its potential for consistent use in occupational health evaluations.
Area of Science:
- Occupational Health
- Ergonomics
- Musculoskeletal Disorders
Background:
- The Strain Index is a tool used to assess workplace musculoskeletal stressors.
- It helps predict the risk of distal upper extremity disorders.
- Evaluating the reliability of such tools is essential for accurate risk assessment.
Purpose of the Study:
- To determine the inter-rater reliability of the Strain Index.
- To assess the consistency of Strain Index application by different raters.
- To evaluate the reliability of both task variable assessment and final hazard classification.
Main Methods:
- Fifteen raters evaluated 61 video segments of single-task jobs.
- Raters estimated or measured five Strain Index variables: exertion intensity/duration, efforts/minute, posture, and speed.
- Inter-rater reliability was assessed using Intraclass Correlation Coefficient (ICC) and Kuder-Richardson-20 (KR-20) for hazard classification.
Main Results:
- Inter-rater reliability for task variables ranged from 0.66-0.84 (individuals) and 0.48-0.93 (teams).
- Strain Index scores showed ICC(2, 1) of 0.43 (individuals) and 0.64 (teams).
- Hazard classification reliability was high: KR-20 of 0.91 (individuals) and 0.89 (teams).
Conclusions:
- The Strain Index demonstrates strong inter-rater reliability for hazard classification, vital for occupational risk assessment.
- While Strain Index scores showed moderate reliability, the final hazard classification is consistently determined.
- The findings support the Strain Index's utility in identifying workers at risk for upper extremity disorders.