MPH 6011 Final Exam 2023/2024 Questions with Answers, Exams of Nursing

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MPH 6011 Final Exam 2023/2024 Questions with Answers

1. Which of the following statements is true about analytic and descriptive epidemiology (select only one)?: Analytic epidemiology compares health events between two or more groups to identify causes of those health events
2. A study on the prevalence of diabetes is conducted by randomly selecting 500 people from Pitt county and measuring A1c levels to determine the preva- lence of diabetes. What is being described?: taking a simple random sample
3. A study is conducted by recruiting 100 students aged 11-15 years old from an urban middle school and another 100 students aged 11- years old from a rural middle school. Students are randomized to one of two groups:

1. participate in an afterschool program focusing on exercise and nutrition or 2) do their usual after school activity whatever it may be. What is being described?: Randomization of an intervention program

4. which of the following measures of association are calculated using the incidence proportion in an exposed group and an incidence proportion in an unexposed group (select all that apply)? a. risk difference b. rate difference c. odds difference d. risk ratio e. rate ratio f. odds ratio: a. risk difference

d. risk ratio

5. In a study, the association between smoking and coronary heart disease was investigated by selecting for study a group of 3000 smokers and 5000 non-smokers who were free of disease at baseline. Both groups were followed for the development of coronary heart disease. 84 smokers developed coro- nary heart disease and 87 non smokers did too. 4913 persons did not develop disease and did not smoke. One measure of association relating exposed to unexposed would be:: (84/3000) / (87/5000)
6. A 20 year cohort study generated 30 cases of heart disease in exposed group and 54,308 person years. The unexposed group had 60 cases and 51,477 person-years. The measure of association showed 0.47. The best interpreta- tion of this finding is:: The exposed group had a reduced rate of heart disease compared to unexposed group.
7. T/F: Confidence intervals quantify the variability around a sample estimate- : true
8. Which of the following are true statements about confidence intervals (select all that apply)? a. Smaller samples result in more narrow confidence intervals (better preci- sion) b. Larger samples result in more narrow confidence intervals (better preci- sion) c. The upper and lower bounds of a confidence interval represent the likely range of values for the true measure of association d. 95% confidence intervals remove 95% of the bias in the observed

measure of association: b. Larger samples result in more narrow confidence intervals (better precision) c. The upper and lower bounds of a confidence interval represent the likely range of values for the true measure of association

9. T/F: In studies where the research question is looking at the cause of dis- ease, either a representative sample or a purposive sample can be used.: answer- true
10. A simple random sample has certain assumptions. Which of the options below is an assumption underlying a simple random sample (Select all that apply)? a.The probability of being selected is based on having specific characteristics b. Selection into sample is independent between each member c. The prevalence of health indicators will always be at least 25% d. Probability of selection is the same for everyone: answer- b. Selection into sample is independent between each member d. Probability of selection is the same for everyone
11. The mean blood pressure in a sample of people from a population is 110 over 70. For the sample to be representative of the overall population, the overall population mean would have to be:: answer- Similar to 110 over 70
12. A design feature in experimental studies that creates equal probability in treatment assignment is what?: answer- randomization
13. T/F: One purpose of randomization is to eliminate differences in

measured and unmeasured characteristics between the treated and untreated groups in the study.: answer- true

14. The primary purpose of a double blind study is to:: answer- Avoid provider bias and participant bias
15. Fluoride was introduced into the water supply of Town A on January 1,
16. A study was conducted to compare new occurrence of cavities in children ages 3-10 years living in two towns (Town A and Town B). The towns are located 10 miles apart. New Cavities in children were measured 5 years after fluoride was introduced into the water supply. Fluoride in water reduced cavities. What is the best answer for the type of study design:: Natural experiment
17. T/F: Bias is a systematic error that only occurs during the interpretation of epidemiology results.: false
18. Which of the following can cause selection bias in a cohort study (or RCT) (Select all that apply)? a. Loss to follow-up b. Blinding of study personnel c. Misclassification of self-reported behaviors d. Randomization of treatment: a. Loss to follow-up
19. Which of the following is a way to check how bad of a problem selection bias might be in a study? a. Compare the distribution of characteristics between treated and untreated groups b. Ask a random sample of study participants whether or not they are telling the truth

c. Compare the proportion lost to follow-up in the treated and untreated groups d. Calculate a risk ratio to see if it equals 1.0 or not: c. Compare the proportion lost to follow-up in the treated and untreated groups

19. Which of the following are examples of DIFFERENTIAL misclassification (select all that apply)? a. exposed individuals are more likely to have their disease misclassified than unexposed individuals b. individuals without disease are more likely to have exposure misclassifica- tion than those who do have the disease c. Exposed individuals have the same misclassification of disease as those who are unexposed d. exposed individuals have a different risk of disease than unexposed indi- viduals: a. exposed individuals are more likely to have their disease misclassified than unexposed individuals b. individuals without disease are more likely to have exposure misclassification than those who do have the disease
20. T/F: Differential misclassification always biases the measure of associa- tion towards the null.: false
21. T/F: Retrospective cohort studies are observational studies and prospec- tive cohort studies are experimental studies.: false
22. In a cohort study, several design and implementation problems can impact the validity of the measure of association. Which of the problems below is NOT a potential problem in cohort studies? a. Information bias b. Lack of temporality

c. Loss-to-follow-up d. Exposure misclassification: b. Lack of temporality

23. Which of the following are advantages of a prospective cohort study compared to retrospective cohort studies (Select all that apply)? a. Fewer resources are needed relative to other study designs b. Precise measurement of exposure is possible c. Incidence rates can be calculated d. Many disease outcomes can be studied simultaneously: b. Precise measure- ment of exposure is possible c. Incidence rates can be calculated d. Many disease outcomes can be studied simultaneously
24. In epidemiologic studies of suspected factors of the cause of disease, the essential difference between an observational study and an experimental study is which of the following? a. The exposed and unexposed (or treated and untreated) groups are equal in size in experimental studies, but not in observational studies b. Experimental studies are prospective, but observational studies are not c. A comparison group is used in experimental studies, but not in observation- al studies d. The investigator manipulates who is and who is not exposed (or treated) in an experimental study: d. The investigator manipulates who is and who is not exposed (or treated) in an experimental study
25. Allowing participants to self-administer a questionnaire using a computer or tablet can help minimize which of the following biases? (select all that apply) a. Social desirability bias

b. Interviewer bias c. Misclassification due to poorly worded questions d. Loss to follow-up: a. Social desirability bias b. Interviewer bias

26. Information bias in a study can come from which of the following sources? (select all that apply) a. In accurate participant recall of an exposure b. A participant answering questions the way he thinks the investigator wants them to be answered c. False positives in an assay for a specific biomarker of exposure: a. In accurate participant recall of an exposure b. A participant answering questions the way he thinks the investigator wants them to be answered c. False positives in an assay for a specific biomarker of exposure
27. A researcher wants to study the impact of chemotherapy on incidence of cardiovascular disease among women who have completed treatment for breast cancer. Of particular interest is both the dose and duration of chemotherapy. The investigator uses the electronic medical records from a large hospital system to identify women who completed breast cancer treat- ment (and had no cardiovascular disease at the end of cancer treatment), the dose and duration of the chemotherapy, and if and when cardiovascular disease was diagnosed in the 5 years after chemotherapy treatment. What type of study design is this?: Retrospective observational cohort study
28. A researcher wants to study the impact of a diet high in antioxidants on the incidence of cardiovascular disease among women who have

completed treat- ment for breast cancer. The investigator uses the electronic medical records from a large hospital system to identify women who completed breast cancer treatment (and had no cardiovascular disease at the end of cancer treatment). The investigator mails a food frequency questionnaire to participants asking them to report the specific foods (and amounts) consumed in the last 2 weeks. After five years, the investigator looks to see who was diagnosed with cardiovascular disease based on documentation in the medical record. What type of study design is this?: Prospective observational cohort study

29. T/F: Poorly measured exposures or health outcomes can lead to mis- classification and introduce bias to the measure of association between an exposure and outcome.: true
30. A study of cardiovascular disease mortality among cigarette smokers and non-smokers found an incidence rate of 399 deaths per 100,000 among smokers and an incidence rate 356 deaths per 100,000 among non- smokers. What is the correct association and interpretation of the mortality rate in smokers compared to the mortality rate in non-smokers?: the mortality rate for smokers is 1.12 times higher than the mortality rate for non-smokers
31. T/F: In a case-control study, controls should be selected from the same population that gave rise to the cases.: true
32. T/F: The purpose of selecting a control in case-control studies is to provide information on the exposure distribution of the source population.: true
33. This occurs when enrolling cases and controls in some way that is based on the exposure of interest.: selection bias

34. This occurs in a study because the mother of a child with a birth defect intentionally remembered infections during pregnancy more accurately than the mother of a child who does not have birth defects.: recall bias

35. T/F: You are selecting a control group for a hospital-based study. The case group is lung cancer patients. An unbiased control series of patients are those with emphysema.: false
36. The measure of association in a case-control study is:: odds ratio
37. A study that samples a population at a single moment in time is what kind of study.: cross-sectional
38. T/F: To conduct an ecologic study, the investigator will enroll participants who have the exposure of interest.: false
39. Which of the studies listed below is NEVER an analytic study design? a. case-crossover b. case-control c. cross-sectional d. case-series: d. case series
40. Which of the following study designs are, or can be, retrospective (select all that apply)? a. cohort study b. case-control study c. cross-sectional study d. randomized control trial: a. cohort study b. case-control study
41. What three qualities does a confounder have to satisfy to be considered a confounder?: associated with exposure, outcome, and not on causal pathway
42. T/F: In a study of coffee consumption and lung cancer, lung cancer was three times higher among coffee drinkers than among coffee non- drinkers. A third variable, smoking, is associated with

lung cancer.

However, in this study, smoking is not associated with coffee consumption. Smoking is a confounder.: false

43. T/F: The original crude odds ratio for the association between exposure and outcome was 2.95. After further analysis, the following table was found below. You should conclude that there is no confounding, because the odds ratios for each strata of age are both 1.0: false
44. An investigator studies the association between obesity (BMI e30 versus BMI <30) and mortality due to cardiovascular disease and finds a crude (unadjusted) risk ratio (RR) of 2.5. However, among people who smoked, the RR for the obesity and mortality association is 1.60 while the same RR among non-smokers is 1.59. What should the investigator do when reporting the results?: There is confounding by smoking status, report the RR after adjusting for smoking status
45. Which of the following can be used to control confounding in a study (select all that apply)? a. randomization of exposure (or treatment, or intervention) b. restricting the study or analysis to one category of a confounder (e.g., men only) c. matching cases and controls by one or more confounders d. adjusting for confounders by including them in a multivariable regression- : all of the above
46. If in a case-control study of alcohol use and cardiovascular disease, the researcher statistically adjusted for gender in the analysis, the researcher most likely considers gender to be a(n):: confounder
47. The following scenario describes which type of bias: In a retrospective co- hort study comparing Treatment A vs. Treatment B and mortality,

patients are more likely to receive Treatment A if they have severe disease, while patients with less severe disease are more likely to received Treatment B.: confounding by indication

48. The odds ratio (OR) between beer consumption and headache is 2.0. You wonder if eating pizza or not eating pizza may influence the association between beer consumption and headache. When you stratify by pizza con- sumption the OR between beer consumption and headache is 3.0 for people not eating pizza but 1.0 for people eating pizza. This is an example of:: Effect modification
49. The risk ratio (RR) between smoking and lung cancer is 4.0. Exposure to asbestos chemicals may may influence the association between smoking and lung cancer. Among individuals who were exposed to asbestos, the RR for smoking and lung cancer is 6.0, while among individuals NOT exposed to asbestos the RR for smoking and lung cancer is 3.0. This is an example of:: Effect measure modification
50. If in a case-control study of alcohol use and cardiovascular disease, the researcher chose to report the odds ratio separately for men and women, the researcher most likely considers gender to be a(n):: Effect modifier
51. Bias is any systematic error in which of the following aspects of a study that results in a mistaken estimate of an exposure's effect on the risk of disease? (Select all that apply) a. analysis b. conduct c. design: all of the above

52. T/F: Validity refers to the conclusions epidemiologists make about a pop- ulation based on sampled data.: false

53. Once chance and bias are ruled out as explanations for an association, the next step is to rule out what?: confounding
54. T/F: Randomization is a means of minimizing the role of chance in an association between two variables.: false
55. Which of the following is another way of stating that chance may affect the results of a study? a. Randomization of the exposure may occur b. Random sampling is representative c. Random variation may occur in the study sample: c. Random variation may occur in the study sample
56. Rejecting the null hypothesis even though the null hypothesis is true is an example of which type of error?: Type 1 error
57. T/F: Temporality refers to the concept that case-control studies should be done before cohort studies: false
58. You have conducted a study on bone density and diabetes. Bone density was measured 20 years before the onset of diabetes. As levels of bone density decrease, the risk of diabetes increases. Your finding has been shown using one type of study design in two pilot studies. Using this information, which criteria of causation best fit the description?: Dose- response, temporality
59. Your study of bone density and risk of diabetes finds a risk ratio of 4.0. You have controlled for some confounding, but are worried other types of bias may be present. You consult with other colleagues and discuss how much bias may or may not be present. You conclude that even if the RR of 4.0 is somewhat biased, it is unlikely that there is sufficient bias present that

would reduce the association to completely null. This is an example of which of causal criteria?: Strength of association

60. T/F: Randomized controlled trials (RCTs) are the gold standard for epidemi- ologic (and clinical) study designs. However, they may still suffer from some forms of bias.: true