Epidemiology: nested case-control study: practice question

A PSM question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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PSM · Epidemiology: nested case-control study

Sample item

From a cohort of 20,000 women with stored baseline serum, investigators take every woman who later developed breast cancer plus matched women who stayed free of it, and then assay the stored serum. Which design is this?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Nested case-control study

A nested case-control study draws cases and sampled controls from within a defined cohort, then measures exposure on stored samples. It is efficient for expensive assays and avoids recall bias. Odds ratios are estimated from the sampled set.

Option by option

  • A. Cross-sectional study

    A cross-sectional study measures exposure and outcome at one point in time.

  • B. Historical cohort study

    A historical cohort follows all members from exposure to outcome using past records, not a sample of controls.

  • C. Nested case-control study (correct)

    Correct. Cases and matched controls are sampled from within an existing cohort.

  • D. Ecological study

    An ecological study uses group-level data, not individual serum values.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More PSM questions

Questions about this PSM question

What is the answer to this PSM question?

The best answer is C, Nested case-control study. A nested case-control study draws cases and sampled controls from within a defined cohort, then measures exposure on stored samples.

Why is "Cross-sectional study" not the answer?

A cross-sectional study measures exposure and outcome at one point in time.

Why is "Historical cohort study" not the answer?

A historical cohort follows all members from exposure to outcome using past records, not a sample of controls.

Why is "Ecological study" not the answer?

An ecological study uses group-level data, not individual serum values.

What concept does this question test?

It tests Epidemiology: nested case-control study in PSM. It is efficient for expensive assays and avoids recall bias. Odds ratios are estimated from the sampled set.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Epidemiology: nested case-control study?

Practise biostatistics with small calculations until sensitivity, predictive values and risk measures are automatic. Then use the flashcards and the other PSM questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.