Final answer:
Case-control and longitudinal studies are key methods in epidemiology for investigating the impact of exposure to past risk factors. They retrospectively analyze behaviors to find associations with current health outcomes and track long-term effects to establish links, such as between smoking and cancer.
Step-by-step explanation:
Case-Control Studies for Past Risk Factors:
Studies that can be designed using information primarily on the exposure to past risk factors include case-control studies. Such an epidemiological study compares subjects with a specific trait (cases) to similar subjects without the trait (controls), focusing retrospectively on their past behaviors. The goal is to identify correlations that may suggest causes of current health statuses. For instance, early case-control studies by Doll and Hill in the 1950s investigated the link between smoking and lung cancer. Researchers recorded a strong association between the two by comparing past smoking habits of those with and without lung cancer.
Relative Risk in Epidemiological Studies:
Relative risk is another epidemiological measure used to assess risk factors associated with disease. It's the ratio of the incidence of a health event in an exposed group to the incidence in a non-exposed group. For example, by comparing cancer rates among smokers to non-smokers, researchers have established crucial links between smoking and increased cancer risk, further validated through longitudinal studies.
Longitudinal Studies and Archival Research:
Longitudinal studies track participants over a prolonged period, like the American Cancer Society's prevention studies, which have yielded significant insights into cancer risk factors. Archival research is another method that deals with historical data to find patterns or predictors, such as factors contributing to the completion of education among college students. Both approaches are vital for understanding the effects of past exposures on current health outcomes.