Study design: 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 · Study design

Sample item

What is a nested case-control study?

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

The answer and the reasoning

B. Case-control study conducted within a defined cohort

Nested case-control studies select cases and controls from an existing cohort, preserving temporal exposure information while reducing costly measurements.

Option by option

  • A. Ecological comparison of countries

    Country comparisons are ecological.

  • B. Case-control study conducted within a defined cohort (correct)

    Correct: sampling occurs within established cohort.

  • C. Survey of only exposed people

    Exposed-only survey is not nested design.

  • D. Trial with no control group

    It still has controls.

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 B, Case-control study conducted within a defined cohort. Nested case-control studies select cases and controls from an existing cohort, preserving temporal exposure information while reducing costly measurements.

Why is "Ecological comparison of countries" not the answer?

Country comparisons are ecological.

Why is "Survey of only exposed people" not the answer?

Exposed-only survey is not nested design.

Why is "Trial with no control group" not the answer?

It still has controls.

What concept does this question test?

It tests Study design in PSM. The correct option holds because: Correct: sampling occurs within established cohort.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Study design?

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.