Comparison of a traditional questionnaire with an icon/calendar-based questionnaire to assess occupational history

Background Self-reported work histories are an essential tool for estimatin g exposure in many occupational epidemiologic studies. However, the transie nce of some occupations such as farm work can hamper recall, resulting in i naccurate reporting. To address this problem, we have developed an icon/cal endar-based questionnaire. This study compares work histories collected via this questionnaire to those collected via a traditional questionnaire. Methods Eighty-nine farmworkers and non-farmworkers were interviewed twice, 8-10 months apart, about their lifetime employment. In the first interview , subjects were asked to recount their entire work history, starting from t he interview date and moving backwards in time ("traditional questionnaire" ). In the second interview, subjects were first asked about important life events, which were recorded with icons on a calendar They were then asked t o recount their work history, which was recorded, job-by-job, on the calend ar with icons ("icon-calendar questionnaire"). Results Number of jobs and amount of work time accounted for since first em ployment were significantly greater using the icon-calendar questionnaire t han the traditional questionnaire, the disparity increasing with time from the date of interview. The ratio of number of jobs in the traditional quest ionnaire to number of jobs in the icon-calendar questionnaire decreased fro m 100.0% in the most recent time period to 0.0% in the earliest time period . While the percentage of time explained by employment remained relatively constant across time periods in the icon-calendar questionnaire, ranging fr om 86.3 to 98.9%, it rapidly decreased with time in the traditional questio nnaire, from 77.9% in the most recent time period to 0.0% in the earliest t ime period. Conclusions The icon-calendar questionnaire was more effective than the tra ditional questionnaire for obtaining complex work histories during intervie ws, producing a more complete picture of a person's work history. published 2001 Wiley-Liss, Inc.