Objectives This study determined the accuracy of workers in quantifying occupational physical demands on a self-administered questionnaire.

Methods First, a self-administered questionnaire on work postures, manual materials-handling, and repetitive upper-limb movements was validated using direct simultaneous observations for 123 randomly selected employees from 6 occupational settings.

Second, weight estimation accuracy was assessed on visual analogue scales for 6 manual materials-handling activities using 20 randomly selected employees from I occupational setting.

Results At a dichotomous level (ever-never), the accuracy of most of the self-reported physical demands was good (sensitivity 60-100% ; specificity 56-100%). A more-detailed analysis of the dimensions studied (frequency, duration and amplitude) also showed that the accuracy of the self-reported estimates was satisfactory.

Full agreement between the estimated and observed frequency was>60% for most of the manual materials-handling activities.

In addition the average difference between the estimated and observed duration of the physical demands was found to be small.

Finally the average difference between the self-reported and actual weights of various loads was found to be modest. (...)