George Washington University PubH 6003: Principles and Practice of Epidemiology. Week 6 Quiz Key

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1 PubH 6003: Principles and Practice of Epidemiology Week #6 Quiz: Please circle or write in the correct answer to each question. 1. In a study begun in 1965, a group of 5,000 healthy adults resid ... ing in St. Louis were asked about dietary patterns. The occurrence of cases of coronary heart disease was studied in this group between 1966-1995. This is an example of a: A. Case-control study B. Cross-sectional study C. Clinical trial D. Retrospective cohort study E. Prospective cohort study 2. In a prospective-cohort study of smokers and non-smokers, the following rates of bladder cancer per 100,000 person-years (PY) were observed (Table 1) Table 1: Rates of Bladder Cancer by Gender and Smoking Status Smokers Non-Smokers Males 46/100,000 PY 12/100,000 PY Females 11/100,000 PY 4/100,000 PY Among males, what would be the relative risk of bladder cancer for smokers compared to nonsmokers? A. 2.0 B. 3.8 C. 32 / 100,000 PY D. 0.3 E. 1.0 3. Which type of study design is best suited for the investigation of a rare disease? A. Clinical trial B. Case-Control study C. Cross-sectional study D. Cohort study E. Ecologic study 4. The odds ratio is an appropriate estimation of the relative risk when: A. The disease in question is rare B. The number of cases approximates the number of controls C. The base population is large D. The cases are based on prevalence data E. The degree of statistical significance is small 2 5. An epidemiologic study was undertaken to determine the relationship between alcohol consumption and the occurrence of laryngeal cancer. Estimates of mean levels of per capita alcohol consumption in New York State and Illinois were compared to the incidence rates of laryngeal cancer in these two states during the same time frame. Incident cases of laryngeal cancer were identified from the state cancer registries. The incidence rates of laryngeal cancer were shown to increase with increasing per capita consumption of alcohol. What type of study was this? A. Cross-sectional study B. Census survey C. Cohort study D. Case-control study E. Ecologic study 6. Which of the following statements describes a major advantage of randomly assigning study participants to the different treatment groups in a clinical trial? A. it avoids observer bias B. it lends itself to ethical justification C. it always leads to results generalizable to the population-at-large D. it minimizes selection bias E. it reduces the likelihood of non-compliance 7. The concept of the “ecologic fallacy” refers to: A. Assessing exposure in large groups rather than in many small groups B. Assessing outcome in large groups rather than in many small groups C. Ascribing the characteristics of a group to every individual in that group D. Failure to examine temporal relations between exposure and outcome E. Examining correlations of exposure and outcomes rather than time trends 8. Retrospective cohort studies are characterized by all of the following except: A. They are useful for studying the effects of rare exposures B. They are not very useful for studying diseases with long latency periods C. The required sample size is similar to that needed for a prospective cohort study D. The study groups may consist of exposed and unexposed cohort members 9. Which type of study is best suited for the investigation of a rare exposure? A. Clinical trial B. Cohort study C. Cross-sectional study D. Case-control study E. Ecologic study 3 The following data were collected in a cross-sectional study: Stress Level With Migraines W/O Migraines Total High Stress 120 204 324 Low Stress 60 816 876 Total 180 1020 1200 10. From these data, the Prevalence Odds Ratio that examined the correlation between high stress levels and migraine headaches was calculated to be: A. 5.4 B. 2.0 C. 0.1 D. 8.0 E. Can’t calculate from data given 4 [Show More]

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