Epidemiology: reliability: 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: reliability

Sample item

Two radiologists independently read the same 100 chest films as normal or abnormal. The investigators want a statistic that measures how well they agree beyond what would be expected by chance. Which should they use?

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

The answer and the reasoning

A. Cohen's kappa

Kappa measures inter-observer agreement for categorical ratings after correcting for agreement expected by chance. A value of 1 indicates perfect agreement and 0 indicates agreement no better than chance. Simple percentage agreement overstates reliability because some agreement occurs by chance alone.

Option by option

  • A. Cohen's kappa (correct)

    Correct. Kappa quantifies agreement beyond chance between two raters.

  • B. Chi-square test

    Chi-square tests association between categories and can be significant even with poor agreement.

  • C. Relative risk

    Relative risk compares incidence between exposed and unexposed groups and is not a measure of agreement.

  • D. Sensitivity

    Sensitivity measures validity against a reference standard, not agreement between two observers.

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, Cohen's kappa. Kappa measures inter-observer agreement for categorical ratings after correcting for agreement expected by chance.

Why is "Chi-square test" not the answer?

Chi-square tests association between categories and can be significant even with poor agreement.

Why is "Relative risk" not the answer?

Relative risk compares incidence between exposed and unexposed groups and is not a measure of agreement.

Why is "Sensitivity" not the answer?

Sensitivity measures validity against a reference standard, not agreement between two observers.

What concept does this question test?

It tests Epidemiology: reliability in PSM. A value of 1 indicates perfect agreement and 0 indicates agreement no better than chance. Simple percentage agreement overstates reliability because some agreement occurs by chance alone.

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: reliability?

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.