Sample exam questions for Introduction to Epidemiology and Public Health

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2. An epidemiologist in Tanzania wants to study the efficacy of iron supplementation for the prevention of HIV infection. He wants to make sure that only subjects who are (still) free of HIV infecti... on are enrolled in his trial. Therefore, he screens a large group of people using a diagnostic test. Based on the outcome of the test, he decides who could participate in his iron supplementation trial. For this purpose, it is very important that the diagnostic test has a high... a. sensitivity b. positive predictive value c. specificity d. negative predictive value 13. A diabetes test is being applied in a population of 5000 men. Previous evaluation of the diabetes test in a different population showed a sensitivity of 70% and an specificity of 80%. The prevalence of diabetes is 0.5%.
 What is the diagnostic value of a positive test in this situation? a. 2 % b. 47 % c. 4 % d. 70 % Page 3!14. Information bias in a cohort study can be avoided by ensuring that...
 Indicate all that apply.
 
 no competing diseases do occur.
 follow-up is complete.
 the persons who assess the disease are not aware of the exposure of the participant.
 disease assessment is highly standardized.
 the persons who collect the data are not aware of the study hypothesis. 15. A cohort study shows a RR of 1.8 (95% CI 1.4-2.2) for alcohol consumption and breast cancer. Another cohort study shows a RR of 1.8 (95% CI 0.6-3.5) for smoking and breast cancer.
 What can be concluded from the results of this study?
 Indicate all that apply.
 
 Both associations are likely to be due to chance.
 Both associations are biased.
 The study on smoking is probably smaller than the study on alcohol.
 Alcohol and smoking both cause breast cancer. 16. When studying diet and risk of chronic diseases, a cohort study generally has the following advantage compared to a case-control study: a. Potential confounders can be taken into account b. Selection bias does not occur c. Various dietary exposures can be studied at the same time d. It has higher internal validity 17. What is a disadvantage of a cohort study compared to a clinical trial? a. The external validity is lower b. It is more prone to confounding c. It is less suitable for studying clinical outcomes d. Participants can drop out during follow-up 18. The Framingham Study, in which a group of residents have been followed since the 1950s to identify occurrence and risk factors for heart disease, is an example of which type(s) of study?
 
 cohort
 case-control
 experimental
 observational
 clinical trial
 cross-sectional 19. Researchers prospectively follow a group of 100 vegetarians and 200 non-vegetarians.
 After 30 years of follow-up, 8 of the vegetarians and 20 of the non-vegetarians develop heart disease. The 95% confidence interval on the relative risk of 0.8 ranges from 0.6 to 0.9.
 Select the best statement. a. Vegetarians were 80% less likely to develop heart disease during 30 years of follow-up compared to. non-vegetarians. b. The researchers should have calculated an odds ratio rathe [Show More]

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