VALIDITY OF A DIARY ESTIMATING EXPOSURE TO TASKS, ACTIVITIES, AND POSTURES OF THE TRUNK

The validity of a diary that estimates exposure to tasks, activities, and postures of the trunk was determined by comparing these self-repor ted exposure data with observational data of a whole working day. Two populations were studied: 32 professional drivers and five nurses. The nurses and 16 drivers also filled out a shortened version of the diar y during another working day. Both versions of the diary showed poor a greement with observations over the same period. However, for variable s concerning activities and postures of the trunk agreement was improv ed by the shortening of the diary. It is concluded that in epidemiolog ic studies observational measurements of exposure cannot validly be re placed by diaries or similar self-reported exposure data, because the self-reports easily lead to misclassification.