Test‐retest reliability of an icon/calendar‐based questionnaire used to assess occupational history

Abstract

Background Self-reported work histories can be critical for both epidemiologic and clinical purposes. However, the complexity of some work histories, such as those of migrant farm workers, can hamper recall, resulting in inaccurate reporting. Memory aids may reduce such error. This study assesses the reliability of work histories collected using such aids in the form of an icon/calendar-based questionnaire. Methods Thirty-one males engaged in farmwork and other manual labor for a median 28 years (range: 10±64) were interviewed twice, 8±14 months apart, about their lifetime employment. In each interview, subjects were asked about important life events, which were recorded with icons on a calendar. They were then asked to recount their work history, including for each job the tasks, crops or products handled, starting and ending dates, and location. This information was recorded, job-by-job, on the calendar with icons. Results Interquestionnaire agreement of cumulative reported employment duration (as measured by the correlation coef®cient) was moderate to high across all time periods for certain crops (e.g., r 0.69±0.92 for apple-related work), by location (e.g., r 0.76±0.95 for Washington State), and for agricultural work in general (r 0.67±0.94), but was lower for speci®c tasks. Agreement of job counts was high for total work history for certain crops (e.g., r 0.93 for apple-related work), by location (e.g., r 0.90 for Washington State), and for agricultural work in general (r 0.89), but paradoxically decreased with proximity to the interview date. Agreement of both measures tended to be highest for those tasks and crops in which subjects reported spending the most time. Categorization of subjects into tertiles on the basis of either cumulative duration or counts produced results similar to those observed for job counts. Conclusions The icon-calendar questionnaire is an effective tool for estimating cumulative duration of certain work categorizations among subjects with complex work histories. Am. J. Ind. Med. 40:512±522,

Development of a life events/icon calendar questionnaire to ascertain occupational histories and other characteristics of migrant farmworkers

“…We had no of®cial preexisting work records with which to compare the reported work histories, so we could not rigorously assess the validity of the self-reported histories [Engel et al, 2001a]. There were several indications that the information was of reasonable quality, however.…”

Ascertainment of occupational histories in the working population: The occupational history calendar approach

“…Complex transient work histories, encountered among migrant farm workers, were more complete when collected using an icon/life events calendar compared with a traditional questionnaire [Engel et al, 2001a]. This same icon/calendar-based questionnaire displayed good reliability in recalling cumulative time undertaking work tasks [Engel et al, 2001b].…”

Comparability of data obtained from migrant farmworkers and their spouses on occupational history†

“…The work histories were obtained by interviewing subjects with an icon/calendar questionnaire, which consists of a calendar in which a subject's major life events are recorded, providing reference points to facilitate recall of speci®c jobs, and icons representing life events and jobs, which builds an easily-interpretable representation of the subject's life/work history. The icon/calendar questionnaire has been shown to produce a more complete picture of farmworkers' work histories than a traditional questionnaire [Engel et al, 2001]. Because there are no available records with which to validate the reported information, we used the self-reported work histories as the``gold standard'' for determining the accuracy of the wives' responses.…”