NR-503 Epidemiology Final Question and
Answer 2026/2027 | Grade A+ Verified | Core
Topics
• You are investigating the role of physical activity in heart disease and suggest that
physical activity protects against having a heart attack. While presenting these data to
your colleagues, someone asks if you could have thought about confounders such as
factor X. This factor X could have confounded your interpretation of the data if it: -✓✓is
a factor associated with physical activity and heart disease
• The strategy which is NOT aimed at reducing selection bias is: -✓✓Standardized
protocol for structured interviews
• *Which is NOT a method for controlling the effects of confounding in epidemiological
studies? -✓✓Blinding
• The purpose of a double-blind study is to: -✓✓avoid observer and interviewee bias
• Techniques to reduce information bias include the following -✓✓All of the above
• *A double-blind study of a vaccine is one in which: -✓✓Neither observers nor subjects
know which subject receives the vaccine and which receives a placebo
• *Surgeons at hospital X report that the mortality rate at the end of a 1-year follow-up
after new coronary bypass procedure is 15%. At hospital Y, the surgeons report a 1-
year mortality rate of 8% after the same procedure. Before concluding that the surgeons
of hospital Y are superior, what possible confounding factors should be examined? -✓✓-
the severity (stage) of disease of the patients at the two hospitals at baseline
-the start of the one-year follow-up at both hospitals (after operation vs after discharge)
-differences in postoperative care at the two hospitals
-equality of follow-up for mortality
ALL OF THE ABOVE
• *sensitivity and specificity of a screening test refer to its -✓✓Validity
• *A test that determines whether disease is actually present is: -✓✓Diagnostic test
• *Based on the information provided, which of the following expresses the
SENSITIVITY of this test:The next two questions refer to the following information:A
screening examination was performed on 250 persons for Factor X, which is found in
disease Y. A definitive diagnosis for disease Y among the 250 persons had been
obtained previously. The results of diagnoses are charted here:Test ResultsDisease
PresentDisease AbsentPositive for Factor X40 60Negative for Factor X10 140 -✓✓80%
, • *Based on the information provided, which of the following expresses the
SPECIFICITY of this test:The next two questions refer to the following information:A
screening examination was performed on 250 persons for Factor X, which is found in
disease Y. A definitive diagnosis for disease Y among the 250 persons had been
obtained previously. The results of diagnoses are charted here:Test ResultsDisease
PresentDisease AbsentPositive for Factor X40 60Negative for Factor X10 140 -✓✓70%
• *You are investigating the role of physicalactivity in heart disease and suggest physical
activity protects against having a heart attack -✓✓is a factor associated with
both,physical activity and heart disease
• *The condition favorable to population screening for pre-symptomatic diagnosis of a
given disease include:
1. a relatively high prevalence of the disease
2. availability of effective treatment
3. a screening test with a high degree of sensitivity
4. availability of physicians to perform the screening test prodecure
Which of the above statements are correct -✓✓1,2 and 3 only
• *The adverse consequences of using a screening test that has a low specificity
include:
1. unnecessarily subjecting people to potential risks associated with diagnostic
procedures
2. over-referral of persons without disease for diagnosis
3. increasing the number of persons who are classified as abnormal
4. failure to identify persons who have the condition
Which of the above statements is/are correct ? -✓✓1,2 and 3 only
• *A new blood test has been developed to screen for disease Z. Researchers establish
50 units as cut point above which a test is considered positive and thereby indicative of
disease. The test manufacturers determine that the test's sensitivity is unacceptably
low. However, the manufacturers are not concerned with the specificity and do not want
the cost of the test to rise. How can they improve the sensitivity of the test? -✓✓lower
the cut point below 50 units
• *An epidemiological experiment is performed in which one group is exposed to a
suspected factor and the other is not. All individuals with an odd hospital admission
number are assigned to the second group. The main purpose of this procedure is to: -
✓✓improve the likelihood that the two groups will be comparable with regard to know
and unknown confounding factors
• *Select from the below options which one is the purpose of matching in a case-control
study -✓✓selection of the controls in such a way that the control group has the same
distribution as the cases with respect to certain confounding variables.
Answer 2026/2027 | Grade A+ Verified | Core
Topics
• You are investigating the role of physical activity in heart disease and suggest that
physical activity protects against having a heart attack. While presenting these data to
your colleagues, someone asks if you could have thought about confounders such as
factor X. This factor X could have confounded your interpretation of the data if it: -✓✓is
a factor associated with physical activity and heart disease
• The strategy which is NOT aimed at reducing selection bias is: -✓✓Standardized
protocol for structured interviews
• *Which is NOT a method for controlling the effects of confounding in epidemiological
studies? -✓✓Blinding
• The purpose of a double-blind study is to: -✓✓avoid observer and interviewee bias
• Techniques to reduce information bias include the following -✓✓All of the above
• *A double-blind study of a vaccine is one in which: -✓✓Neither observers nor subjects
know which subject receives the vaccine and which receives a placebo
• *Surgeons at hospital X report that the mortality rate at the end of a 1-year follow-up
after new coronary bypass procedure is 15%. At hospital Y, the surgeons report a 1-
year mortality rate of 8% after the same procedure. Before concluding that the surgeons
of hospital Y are superior, what possible confounding factors should be examined? -✓✓-
the severity (stage) of disease of the patients at the two hospitals at baseline
-the start of the one-year follow-up at both hospitals (after operation vs after discharge)
-differences in postoperative care at the two hospitals
-equality of follow-up for mortality
ALL OF THE ABOVE
• *sensitivity and specificity of a screening test refer to its -✓✓Validity
• *A test that determines whether disease is actually present is: -✓✓Diagnostic test
• *Based on the information provided, which of the following expresses the
SENSITIVITY of this test:The next two questions refer to the following information:A
screening examination was performed on 250 persons for Factor X, which is found in
disease Y. A definitive diagnosis for disease Y among the 250 persons had been
obtained previously. The results of diagnoses are charted here:Test ResultsDisease
PresentDisease AbsentPositive for Factor X40 60Negative for Factor X10 140 -✓✓80%
, • *Based on the information provided, which of the following expresses the
SPECIFICITY of this test:The next two questions refer to the following information:A
screening examination was performed on 250 persons for Factor X, which is found in
disease Y. A definitive diagnosis for disease Y among the 250 persons had been
obtained previously. The results of diagnoses are charted here:Test ResultsDisease
PresentDisease AbsentPositive for Factor X40 60Negative for Factor X10 140 -✓✓70%
• *You are investigating the role of physicalactivity in heart disease and suggest physical
activity protects against having a heart attack -✓✓is a factor associated with
both,physical activity and heart disease
• *The condition favorable to population screening for pre-symptomatic diagnosis of a
given disease include:
1. a relatively high prevalence of the disease
2. availability of effective treatment
3. a screening test with a high degree of sensitivity
4. availability of physicians to perform the screening test prodecure
Which of the above statements are correct -✓✓1,2 and 3 only
• *The adverse consequences of using a screening test that has a low specificity
include:
1. unnecessarily subjecting people to potential risks associated with diagnostic
procedures
2. over-referral of persons without disease for diagnosis
3. increasing the number of persons who are classified as abnormal
4. failure to identify persons who have the condition
Which of the above statements is/are correct ? -✓✓1,2 and 3 only
• *A new blood test has been developed to screen for disease Z. Researchers establish
50 units as cut point above which a test is considered positive and thereby indicative of
disease. The test manufacturers determine that the test's sensitivity is unacceptably
low. However, the manufacturers are not concerned with the specificity and do not want
the cost of the test to rise. How can they improve the sensitivity of the test? -✓✓lower
the cut point below 50 units
• *An epidemiological experiment is performed in which one group is exposed to a
suspected factor and the other is not. All individuals with an odd hospital admission
number are assigned to the second group. The main purpose of this procedure is to: -
✓✓improve the likelihood that the two groups will be comparable with regard to know
and unknown confounding factors
• *Select from the below options which one is the purpose of matching in a case-control
study -✓✓selection of the controls in such a way that the control group has the same
distribution as the cases with respect to certain confounding variables.
