Ergonomics case study: revised NIOSH lifting equation instruction issues for students

This case study investigated the effectiveness of formal instruction of the Revised NIOSH Lifting Equation for university students who may use the equation in their future work. Their successes and challenges were examined through a class exercise and two exams, all of which followed the classroom instruction in applying the Lifting Equation. Results showed students (1) had difficulty determining relevant values for task variables from reading a job description, and (2) generally were able to calculate the Recommended Weight Limit (RWL) and Lifting Index (LI) when task variables were such that the associated multipliers were less than or equal to 1. However, when the multiplier was calculated to be greater than 1, students had difficulty interpreting the result. The task variable and multiplier (consistently the greatest challenge) were the asymmetry task variable, A, and the asymmetric multiplier, AM. Results indicate that the layout of the Job Analysis Worksheet for Step 1 may make it easy to make arithmetic errors when calculating multipliers. It is recommended that the worksheet be redesigned to help individuals decrease the probability of making an arithmetic error when calculating the task variables, multipliers, RWL, and LI. It is also recommended that the redesigned worksheet be tested to determine whether fewer arithmetic errors are made and if the worksheet is less confusing for an inexperienced user to use.