Assertion: In a nested case-control study, incidence rates can be derived from the parent cohort. Reason: Nested case-control studies have the ability to estimate relative risk accurately.

Appeared in: INI-CET EXAM -2026

Explanation

The assertion is correct. A nested case-control study is embedded within a parent cohort. The cohort follows a defined population over time, which allows for the direct calculation of incidence rates (new cases over time).
The reason is also correct. A key strength of the nested case-control design is its sampling method (selecting controls from the risk set when a case occurs), which allows the odds ratio to be an accurate, unbiased estimate of the relative risk.
The two statements are unrelated. The ability to calculate incidence comes from the parent cohort structure, while the accurate risk estimation comes from the specific case-control sampling strategy used within that cohort. The latter does not explain the former.

Option A: This is incorrect because while both statements are true, the reason does not explain the assertion. The ability to estimate relative risk accurately is a consequence of the sampling design, not the reason why incidence rates can be calculated.
Option C: This is incorrect because the reason is a valid and important feature of nested case-control studies. They are known for providing accurate estimates of relative risk.
Option D: This is incorrect because the assertion is true. The parent cohort provides the necessary data (population at risk and follow-up over time) to calculate incidence rates.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Nested Case-Control Study Design as background academic context rather than a clinical decision trigger.
This study design is highly efficient for nursing research when investigating the causes of rare diseases or when exposure assessment (e.g., genetic testing, biomarker analysis) is expensive.
It allows researchers to use stored biological samples from a large cohort study to investigate new hypotheses without the cost and time of analyzing samples from the entire cohort.
What if? If the study were a traditional case-control study (not nested in a cohort), the assertion would be incorrect. Traditional case-control studies start with diseased and non-diseased individuals and look backward, so they cannot calculate incidence rates.

How to Approach the Question

Step 1: Analyze the Assertion. Determine if the statement is factually correct. Is it true that incidence rates can be derived in a nested case-control study? Yes, this is possible because it is based within a parent cohort.
Step 2: Analyze the Reason. Determine if this second statement is also factually correct. Is it true that these studies accurately estimate relative risk? Yes, this is a known strength of the design.
Step 3: Evaluate the Relationship. Assess if the Reason is the correct explanation for the Assertion. Does the ability to estimate relative risk explain why you can calculate incidence rates? No, these are two separate features of the study design.
Step 4: Select the appropriate option. Since both statements are true but unrelated, choose the option that reflects this (Both A and R are true, but R is not the correct explanation of A).

Concept Tested & Keywords

Concept Tested: Nested Case-Control Study Design
Stem keywords: nested case-control study, incidence rates, parent cohort, relative risk
Lead-in keywords: Assertion, Reason

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E6 NursingResearch Suresh Sharma 5e Part 1 p. 185-187

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 72-74

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