An Analysis of Task-Based Worker Self-Assessments of Force

Abstract

Worker self-assessments are an important tool for assessing force and effort in physical work. This study uses maximal grip exertions on a dynamometer to calibrate the workers before rating various tasks' force requirements on a 0 to 10 visual analog scale. 78 workers were selected on 58 different jobs at an automotive assembly plant and asked to rate the separate tasks and the job as a whole. Their peak force ratings (6+2.5) were significantly higher than those estimated by trained observers (4.7+1.1), however they used a larger range of values on the force scale suggesting they were more sensitive to subtle changes. Worker ratings were also sensitive to Hand Activity Level (HAL) changes. Workers on the same job selected the same task to define peak force 86.4% of the time. In conclusion, worker self-ratings can be helpful tool in identifying tasks with high force requirements.