Epidemiology: cross-sectional study limitation: 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: cross-sectional study limitation

Sample item

The main limitation of a cross-sectional study in establishing causation is that it:

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

The answer and the reasoning

D. Cannot establish temporal sequence between exposure and outcome

Exposure and outcome are measured at the same point in time, so one cannot tell which came first. Cross-sectional studies are quick and give prevalence, and they are useful for generating hypotheses.

Option by option

  • A. Cannot measure prevalence

    Measuring prevalence is the main strength of the design.

  • B. Cannot be used for hypothesis generation

    It is useful for generating hypotheses.

  • C. Needs a long follow-up

    Long follow-up is a feature of cohort studies, not cross-sectional ones.

  • D. Cannot establish temporal sequence between exposure and outcome (correct)

    Correct. Temporality cannot be established.

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.

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Questions about this PSM question

What is the answer to this PSM question?

The best answer is D, Cannot establish temporal sequence between exposure and outcome. Exposure and outcome are measured at the same point in time, so one cannot tell which came first.

Why is "Cannot measure prevalence" not the answer?

Measuring prevalence is the main strength of the design.

Why is "Cannot be used for hypothesis generation" not the answer?

It is useful for generating hypotheses.

Why is "Needs a long follow-up" not the answer?

Long follow-up is a feature of cohort studies, not cross-sectional ones.

What concept does this question test?

It tests Epidemiology: cross-sectional study limitation in PSM. Cross-sectional studies are quick and give prevalence, and they are useful for generating hypotheses.

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 Epidemiology: cross-sectional study limitation?

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.