Time lines and computer-based visual editing: new techniques for assessing exposure in epidemiologic studies.

We describe a time-line-based methodology for collecting exposure data for epidemiologic studies and for processing these data for statistical analysis with readily available software for the personal computer. The four components to this approach are: (1) collecting data in a memory-enhancing time-line format; (2) entering data from time lines into a computer database and editing them; (3) making a quantitative estimate of exposure, intake, or dose for each exposure event; and (4) creating analysis datasets by 'slicing' the quantified time lines based on desired exposure intervals or disease latent periods. Compared with fixed-format interviews, time-line-based interviews help subjects organize remembered events, thereby reducing confusion. They do not restrict responses to predetermined categorical exposure responses. The time-line methodology also facilitates the collection of supplementary data necessary for computing doses for complex exposures and the packaging of quantified exposures into analysis datasets for any time period of interest.