Select the most appropriate study design for each of the following questions. (Note: All study design options may not be used and each design option can be used more than once.

1. A study is done to examine the association between a mother’s education and risk of a congenital heart defect in her offspring. The investigator enrolls a group of mothers of babies with birth defects and a group of mothers of babies without birth defects. The mothers are then asked a series of questions about their education.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
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2. 2. A study on the association of coffee consumption and performance on a memory test randomly assigns half of the enrolled subjects to drink coffee one hour before taking the memory test and the other half to not drink coffee one hour before taking the memory test.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
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3. 3. A study examining the association between meat consumption and heart disease compares the average number of kilograms of meat consumed per person for 50 different countries to the incidence rate of heart disease in the same 50 countries.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
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4. 4. An investigator enrolls a group of healthy individuals and distributes questionnaires to collect information on sex and blood type. The investigator then examines the association between sex and blood type.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
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5. 5. A study describes a group of hospital patients all of whom suffer from migraine with aura and experienced an ischemic stroke.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
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6. 6. A study recruits a group of college graduates. At the time of recruitment, participants provide a blood sample that is immediately stored and they complete a questionnaire about lifestyle behaviors. The participants are followed over time to see who develops Parkinson’s Disease. Two studies are performed. Classify each study.
a) In one study, the researchers compare people reporting regular physical activity to those who are sedentary.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
b) In another study, the stored blood sample for each case is compared to the blood sample for a non-case that was alive and at risk on the day that the case was diagnosed with Parkinson's disease. The blood samples are analyzed to see if serum levels of Vitamin D are associated with the risk of developing Parkinson’s disease.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
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7. 7. A researcher uses a database of medical records to identify a group of retired factory workers. He reviews each person’s medical records to follow their factory exposures over time and see which of these subjects has developed skin cancer in the past 25 years.
Case series Case-control study Nested case-control study Prospective cohort study Retrospective cohort study Randomized clinical trial Cross-sectional study Ecological study Case cohort study
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LOL. Not homework. This is the exam for an edX course. Free course. Certificate is just a bit of digital paper. But there are those who are desperate for the certificate. Why?

1. Case-control study: In this study design, the investigator enrolls a group of mothers of babies with birth defects (cases) and a group of mothers of babies without birth defects (controls). The mothers are then asked questions about their education to examine the association between the mother's education and the risk of a congenital heart defect in her offspring.

2. Randomized clinical trial: In this study design, the subjects are randomly assigned to two groups: one that drinks coffee one hour before taking the memory test and the other that does not drink coffee. The study aims to examine the association of coffee consumption with performance on a memory test.

3. Ecological study: In this study design, the average meat consumption per person for 50 different countries is compared to the incidence rate of heart disease in the same countries. The study aims to examine the association between meat consumption and heart disease at a population level.

4. Cross-sectional study: In this study design, a group of healthy individuals is enrolled, and questionnaires are used to collect information on sex and blood type. The association between sex and blood type is then examined. This study design allows for observing the prevalence of an exposure (sex) and an outcome (blood type) at a specific point in time.

5. Case series: In this study design, a group of hospital patients who suffer from migraine with aura and experienced an ischemic stroke is described. A case series involves describing and summarizing the characteristics of a series of individuals with a particular condition but does not involve a comparison group.

6a. Prospective cohort study: In this study, a group of college graduates is recruited, and at the time of recruitment, they provide a blood sample and complete a questionnaire about lifestyle behaviors. The participants are then followed over time to see who develops Parkinson's Disease. The researchers compare people reporting regular physical activity to those who are sedentary to examine the association between physical activity and the development of Parkinson's Disease.

6b. Nested case-control study: In this study, the stored blood samples for each case (individuals who developed Parkinson's Disease) are compared to the blood samples for non-cases (individuals who did not develop Parkinson's Disease) who were alive and at risk on the day the case was diagnosed. The blood samples are analyzed to see if serum levels of Vitamin D are associated with the risk of developing Parkinson's Disease. This study design is nested within the prospective cohort study described in 6a.

7. Retrospective cohort study: In this study design, a researcher uses a database of medical records to identify a group of retired factory workers. The researcher reviews each person's medical records to follow their factory exposures over time and see which of these subjects has developed skin cancer in the past 25 years. The study aims to examine the association between factory exposures and the development of skin cancer retrospectively.