Bias: 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 · Bias

Sample item

What does lead-time bias make appear longer in a screened population?

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

The answer and the reasoning

A. Survival measured from diagnosis without necessarily delaying death

Screening can diagnose disease earlier, extending measured survival from diagnosis even when the time of death remains unchanged.

Option by option

  • A. Survival measured from diagnosis without necessarily delaying death (correct)

    Correct: earlier clock-start can inflate apparent survival.

  • B. True lifespan after disease onset

    Actual lifespan need not change with lead-time bias.

  • C. The disease incubation period

    Incubation period is unrelated to diagnostic timing.

  • D. Test specificity in non-cases

    Specificity is an intrinsic diagnostic test property.

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 A, Survival measured from diagnosis without necessarily delaying death. Screening can diagnose disease earlier, extending measured survival from diagnosis even when the time of death remains unchanged.

Why is "True lifespan after disease onset" not the answer?

Actual lifespan need not change with lead-time bias.

Why is "The disease incubation period" not the answer?

Incubation period is unrelated to diagnostic timing.

Why is "Test specificity in non-cases" not the answer?

Specificity is an intrinsic diagnostic test property.

What concept does this question test?

It tests Bias in PSM. The correct option holds because: Correct: earlier clock-start can inflate apparent survival.

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 Bias?

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.