Epidemiology: attack rate: 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: attack rate

Sample item

At a wedding, 36 of 120 guests who ate egg salad become ill. What is the attack rate among egg-salad eaters?

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

The answer and the reasoning

D. 30%

Attack rate is the proportion of an exposed group that develops illness during an outbreak. Here 36 divided by 120 equals 0.30.

Option by option

  • A. 36%

    Thirty-six is the number of cases, not the percentage.

  • B. 70%

    Seventy percent is not supported by the numerator and denominator.

  • C. 3%

    Three percent would be 3.6 cases per 120.

  • D. 30% (correct)

    Correct. 36/120 equals 30 percent.

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 D, 30%. Attack rate is the proportion of an exposed group that develops illness during an outbreak.

Why is "36%" not the answer?

Thirty-six is the number of cases, not the percentage.

Why is "70%" not the answer?

Seventy percent is not supported by the numerator and denominator.

Why is "3%" not the answer?

Three percent would be 3.6 cases per 120.

What concept does this question test?

It tests Epidemiology: attack rate in PSM. Here 36 divided by 120 equals 0.30.

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: attack rate?

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.