Epidemiologists sometimes collect information on exposure by proxy or surrogate. This may be because the study subjects are deceased or otherwise inaccessible, or even because the investigators are concerned that participants themselves may inaccurately report this information (perhaps they are sick and this impacts their ability to recall exposure, or perhaps they are acutely aware of their exposure status and this makes them more attentive to disease symptoms). Researchers often use medical or occupational records as information surrogates, but an interview with a close family member may be another way to obtain the required detail. As you participate in this discussion, put yourself in the place of a family member being asked to provide this type of information. Consider whether you think you’d be able to provide accurate information, and how that might impact a researcher’s study goals. A researcher conducting an observational study decides to collect information by proxy. You are a 1st degree relative (e.g., mother, father, sister, brother) of an adult who was selected for the study. You are being asked to provide details on the lifestyle habits and occupational exposures of your family member, and you agree to participate in this way as an exposure proxy for the study. The 20-minute interview is conducted in-person, where you are asked about your family member’s smoking, drinking, and dietary habits. You are also asked a series of questions relating to his/her entire professional work history, including places of employment, type of job, hours worked, and exposure to physical or chemical hazards. After the interviewer leaves, you consider the accuracy of your responses. In your opinion, how would you characterize your accuracy as an information proxy for this study? What specifically are you concerned about in regards to recalling these details? Now applying what you’ve learned from the readings and videos, let’s go through the rest of the discussion together. The choice of study design is often based on practical aspects relating to feasibility – the financial costs, use of resources, amount of time, etc. It is sometimes also driven by the availability of information, or the ease with which contacting or maintaining contact with subjects can be achieved. An epidemiologist must weigh the potential threats to study validity (something we will get to in Modules 6 and 7) against these practical concerns. Even without a solid foundation in the language of bias, you have gained enough understanding of the major epidemiologic study designs to make informed decisions about the choice of a particular design. Read the paper by Clough-Gorr et al (Links to an external site.)., which summarizes a case-control study of tanning bed exposure and risk of melanoma. Pay attention to the aspects of the case-control design that you have learned, and contrast them to what you know about other observational designs (cohort, cross-sectional, ecological). Ask yourself how information might have been obtained with an alternative design, and what the advantages and disadvantages of the alternate designs might be. Please respond to the following: How would the research question differ if this study had not been a case-control design, but instead one of the other 3 observational designs you learned about? Generalize as to how the interpretations of the results might differ with this alternate design. Be sure to demonstrate your understanding of the limits of what we can infer from the alternate study design. Predict the key advantages to this study being conducted via a case-control approach, rather than a cohort design. Distinguish these from the disadvantages. Do not provide generic lists, but apply your answer specifically to this study. Recommend changes to various aspects of this study, keeping with the case-control design. You may choose to focus on the study population, sampling of the population, modes of contact, how data were collected, etc.