Epiville

Quizzes

Quiz 2, Module Cohort

2. Based on your hypothesis, what would be the best way to define exposure?

  1. Provide all workers at the Glop Industries manufacturing plant with individual air quality instruments to take daily readings in order to compile weekly doses of exposure to SUPERCLEAN.
  2. Ask workers about their professional activities at the factory and estimate their exposure to SUPERCLEAN.
  3. Look for sources of information at the factory which record individual worker exposures throughout their employment.
Answer (a) — incorrect: While this is a wonderful attempt for precise exposure measurement, it comes a little bit too late in the game. We are interested in exposures that have occurred in the past to see their effect on the development of Susser Syndrome.
Answer (b) — incorrect: Since we have decided to conduct a retrospective cohort study, we need to have information about work-related SUPERCLEAN exposure recorded before the start of the follow-up period. Our study began 2 years ago in September and the follow-up period lasted 2 years. Asking about exposure at the end of the study, when some of those exposed are already ill, may distort your results. For instance, people who developed Susser Syndrome may be more inclined to over-report exposures (i.e., your risk ratio would be inflated).
Answer (c) — correct: In retrospective studies, all relevant events (both exposures and outcomes of interest) have already occurred by the time the study is initiated. Because of this, retrospective studies depend on the routine availability of exposure data from pre-existing records. It is reasonable to assume that the factory will keep track of exposures to chemicals like SUPERCLEAN and would be interested in sharing this information with investigators.