Problem: You are a researcher that is interested in looking at the relationship between smoking (exposure) and lung cancer (outcome). Please provide a brief summary of how you would conduct a study that is either a prospective cohort study, a retrospective cohort study or a case control study. Additionally, think of another variable that you would want to look at that might have a relationship with the exposure and/or outcome that could influence the results seen (i.e. a confounder or an effect modifying variable).