NURS 5240 Statistics and Epidemiology for
Advanced Practice QUESTIONs and well detailed
answers 2026/2027
QUESTION 1
In evaluating a new screening program for a rare chronic illness, an
epidemiologist notes that the disease has a low prevalence in the
general population. What is the primary effect of low disease
prevalence on the positive predictive value (PPV) of a screening test,
assuming sensitivity and specificity remain constant?
• A. PPV will increase significantly.
• B. PPV will decrease, as the proportion of false-positive results
relative to true positives increases.
• C. PPV remains entirely unaffected by disease prevalence.
• D. PPV equals the specificity of the test.
Correct Answer: B. PPV will decrease, as the proportion of false-positive
results relative to true positives increases.
Detailed Rationale: Predictive values depend heavily on the prevalence
of the disease in the population being tested. When a condition is rare,
even a test with high specificity will yield a large number of false
positives compared to the small number of true positives, resulting in a
low PPV.
QUESTION 2
,A researcher conducts a prospective cohort study to evaluate whether
chronic sleep deprivation increases the risk of developing type 2
diabetes. What is the primary measure of association calculated in this
type of study design?
• A. Odds ratio (OR)
• B. Relative risk (RR) or risk ratio
• C. Attributable fraction in the population
• D. Sensitivity and specificity
Correct Answer: B. Relative risk (RR) or risk ratio
Detailed Rationale: Prospective cohort studies begin by classifying
participants by exposure status (e.g., sleep-deprived vs. well-rested)
and following them forward in time to assess disease development.
Because incidence can be directly measured in both exposed and
unexposed groups, the relative risk is the standard measure of
association.
QUESTION 3
A case-control study is designed to investigate the association between
a history of heavy pesticide exposure and the development of Parkinson
disease. Which of the following is a primary methodological advantage
of a case-control study?
• A. It is optimal for studying rare exposures.
• B. It allows for the direct calculation of disease incidence rates.
• C. It is highly efficient and cost-effective for studying rare diseases
with long latent periods.
, • D. It completely eliminates all forms of recall and selection bias.
Correct Answer: C. It is highly efficient and cost-effective for studying
rare diseases with long latent periods.
Detailed Rationale: Case-control studies start with individuals who
already have the outcome (cases) and those who do not (controls), then
look backward for exposures. This makes them exceptionally efficient
and cost-effective for rare diseases or conditions with long induction
periods, though they cannot calculate true incidence directly.
QUESTION 4
In a clinical trial comparing a new antihypertensive medication to
standard care, the analysis yields a p-value of 0.03 for the primary
endpoint of systolic blood pressure reduction, with a pre-set alpha level
of 0.05. What is the correct statistical interpretation of this finding?
• A. The null hypothesis is accepted, proving the new medication
has no effect.
• B. There is a 3% probability that the null hypothesis is true.
• C. The probability of observing a difference at least as large as the
one found, assuming the null hypothesis is true, is 3%, leading to
rejection of the null hypothesis.
• D. The probability of a Type II error is exactly 3%.
Correct Answer: C. The probability of observing a difference at least as
large as the one found, assuming the null hypothesis is true, is 3%,
leading to rejection of the null hypothesis.
Detailed Rationale: A p-value represents the probability of obtaining
test results at least as extreme as the results actually observed, under
, the assumption that the null hypothesis is correct. Since 0.03 is less
than the alpha level of 0.05, the result is considered statistically
significant, and the null hypothesis is rejected.
QUESTION 5
A nurse researcher is studying the relationship between physical activity
levels and serum cholesterol concentrations. The correlation coefficient
(𝑟) between weekly exercise hours and LDL cholesterol is calculated to
be −0.75. How should this statistical value be interpreted?
• A. There is a strong positive linear relationship between exercise
hours and LDL cholesterol.
• B. There is a strong inverse (negative) linear relationship, meaning
higher exercise hours are associated with lower LDL cholesterol
levels.
• C. Exercise causes a 75% reduction in LDL cholesterol synthesis.
• D. There is no statistically significant correlation between the two
variables.
Correct Answer: B. There is a strong inverse (negative) linear
relationship, meaning higher exercise hours are associated with lower
LDL cholesterol levels.
Detailed Rationale: The correlation coefficient (𝑟) ranges from −1.0 to
+1.0. The magnitude (0.75) indicates a strong relationship, and the
negative sign indicates an inverse relationship where an increase in one
variable corresponds to a decrease in the other.
QUESTION 6
Advanced Practice QUESTIONs and well detailed
answers 2026/2027
QUESTION 1
In evaluating a new screening program for a rare chronic illness, an
epidemiologist notes that the disease has a low prevalence in the
general population. What is the primary effect of low disease
prevalence on the positive predictive value (PPV) of a screening test,
assuming sensitivity and specificity remain constant?
• A. PPV will increase significantly.
• B. PPV will decrease, as the proportion of false-positive results
relative to true positives increases.
• C. PPV remains entirely unaffected by disease prevalence.
• D. PPV equals the specificity of the test.
Correct Answer: B. PPV will decrease, as the proportion of false-positive
results relative to true positives increases.
Detailed Rationale: Predictive values depend heavily on the prevalence
of the disease in the population being tested. When a condition is rare,
even a test with high specificity will yield a large number of false
positives compared to the small number of true positives, resulting in a
low PPV.
QUESTION 2
,A researcher conducts a prospective cohort study to evaluate whether
chronic sleep deprivation increases the risk of developing type 2
diabetes. What is the primary measure of association calculated in this
type of study design?
• A. Odds ratio (OR)
• B. Relative risk (RR) or risk ratio
• C. Attributable fraction in the population
• D. Sensitivity and specificity
Correct Answer: B. Relative risk (RR) or risk ratio
Detailed Rationale: Prospective cohort studies begin by classifying
participants by exposure status (e.g., sleep-deprived vs. well-rested)
and following them forward in time to assess disease development.
Because incidence can be directly measured in both exposed and
unexposed groups, the relative risk is the standard measure of
association.
QUESTION 3
A case-control study is designed to investigate the association between
a history of heavy pesticide exposure and the development of Parkinson
disease. Which of the following is a primary methodological advantage
of a case-control study?
• A. It is optimal for studying rare exposures.
• B. It allows for the direct calculation of disease incidence rates.
• C. It is highly efficient and cost-effective for studying rare diseases
with long latent periods.
, • D. It completely eliminates all forms of recall and selection bias.
Correct Answer: C. It is highly efficient and cost-effective for studying
rare diseases with long latent periods.
Detailed Rationale: Case-control studies start with individuals who
already have the outcome (cases) and those who do not (controls), then
look backward for exposures. This makes them exceptionally efficient
and cost-effective for rare diseases or conditions with long induction
periods, though they cannot calculate true incidence directly.
QUESTION 4
In a clinical trial comparing a new antihypertensive medication to
standard care, the analysis yields a p-value of 0.03 for the primary
endpoint of systolic blood pressure reduction, with a pre-set alpha level
of 0.05. What is the correct statistical interpretation of this finding?
• A. The null hypothesis is accepted, proving the new medication
has no effect.
• B. There is a 3% probability that the null hypothesis is true.
• C. The probability of observing a difference at least as large as the
one found, assuming the null hypothesis is true, is 3%, leading to
rejection of the null hypothesis.
• D. The probability of a Type II error is exactly 3%.
Correct Answer: C. The probability of observing a difference at least as
large as the one found, assuming the null hypothesis is true, is 3%,
leading to rejection of the null hypothesis.
Detailed Rationale: A p-value represents the probability of obtaining
test results at least as extreme as the results actually observed, under
, the assumption that the null hypothesis is correct. Since 0.03 is less
than the alpha level of 0.05, the result is considered statistically
significant, and the null hypothesis is rejected.
QUESTION 5
A nurse researcher is studying the relationship between physical activity
levels and serum cholesterol concentrations. The correlation coefficient
(𝑟) between weekly exercise hours and LDL cholesterol is calculated to
be −0.75. How should this statistical value be interpreted?
• A. There is a strong positive linear relationship between exercise
hours and LDL cholesterol.
• B. There is a strong inverse (negative) linear relationship, meaning
higher exercise hours are associated with lower LDL cholesterol
levels.
• C. Exercise causes a 75% reduction in LDL cholesterol synthesis.
• D. There is no statistically significant correlation between the two
variables.
Correct Answer: B. There is a strong inverse (negative) linear
relationship, meaning higher exercise hours are associated with lower
LDL cholesterol levels.
Detailed Rationale: The correlation coefficient (𝑟) ranges from −1.0 to
+1.0. The magnitude (0.75) indicates a strong relationship, and the
negative sign indicates an inverse relationship where an increase in one
variable corresponds to a decrease in the other.
QUESTION 6
