THE ACCURACY OF SELF-REPORT AND TRAINED OBSERVER METHODS FOR OBTAINING ESTIMATES OF PEAK LOAD INFORMATION DURING INDUSTRIAL WORK

The purpose of this study was to determine how well self-report (quest ionnaire = QR) and trained observer (checklist = OBS) data recording m ethods compared with more expensive video analysis (VID) for estimatin g various peak physical loading exposure variables on the low backs of 99 employees during work in an automobile assembly plant. The variabl es studied were L4/L5 spine compression and shear forces, L4/L5 moment , trunk angle, and hand load. Peak low back loads associated with the working postures of, and the applied loads on, each worker were estima ted using a 2D biomechanical model that could accommodate inertial for ces acting in various directions on the hands independently. Correlati ons between the VID and OBS methods were greater for each variable tha n between VID and QR methods, with ranges in coefficients from 0.6 to 0.8, and 0.1 to 0.4, respectively, giving a discouraging impression of the QR, and the OBS method to a lesser degree, for peak low back expo sure assessment. Despite the better performance of OBS method for indi viduals, it was still only able to account for between 36% and 64% of the variance relative to the VID method. When all workers were conside red as a single group, compression and shear forces, moment and hand l oad estimates were the same regardless of method used to collect the d ata. Self-reported trunk flexion was significantly greater than that r eported by trained observers or on video (p < 0.0001). Relevance to in dustry Considerable time and expense could be saved in large scale stu dies if it were possible to rely on worker's reports or observation of the physical demands of their jobs instead of traditional video and b iomechanical analyses. Assessments of peak exposure of individuals usi ng the self-report and observation methods were discouraging. Analysis of a single group proved more promising, but other groups need to be studied. Interview assisted self-reports may help to improve assessmen ts of individuals and also need to be investigated in the future.