Epidemiology: screening in series: 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: screening in series

Sample item

When two screening tests are applied in series (second test only for those positive on the first), the net effect is:

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

The answer and the reasoning

D. Higher specificity and lower sensitivity

In series testing, a person is called positive only if both tests are positive, so false positives fall (specificity rises) while some true cases are missed (sensitivity falls). Parallel testing has the opposite effect.

Option by option

  • A. No change in either

    Combined testing changes performance.

  • B. Higher sensitivity and higher specificity

    Combination cannot raise both simultaneously.

  • C. Higher sensitivity and lower specificity

    This describes parallel testing.

  • D. Higher specificity and lower sensitivity (correct)

    Correct. Series testing raises specificity at the cost of sensitivity.

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, Higher specificity and lower sensitivity. In series testing, a person is called positive only if both tests are positive, so false positives fall (specificity rises) while some true cases are missed (sensitivity falls).

Why is "No change in either" not the answer?

Combined testing changes performance.

Why is "Higher sensitivity and higher specificity" not the answer?

Combination cannot raise both simultaneously.

Why is "Higher sensitivity and lower specificity" not the answer?

This describes parallel testing.

What concept does this question test?

It tests Epidemiology: screening in series in PSM. Parallel testing has the opposite effect.

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: screening in series?

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.