Biostatistics: Poisson distribution: 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.

Try it

PSM · Biostatistics: Poisson distribution

Sample item

The number of new cases of a rare disease reported each month in a district is being modelled. The events are rare, occur independently and have a small constant average rate. Which probability distribution is appropriate?

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

The answer and the reasoning

D. Poisson distribution

The Poisson distribution describes the number of rare, independent events occurring in a fixed interval of time or space with a constant average rate. The normal distribution is for continuous measurements that cluster around a mean. The t distribution is used for means of small samples.

Option by option

  • A. Uniform distribution

    A uniform distribution gives equal probability to all outcomes, which does not fit rare events.

  • B. Normal distribution

    The normal distribution models continuous measurements, not counts of rare events.

  • C. Student's t distribution

    The t distribution is a sampling distribution for means, not for counts of events.

  • D. Poisson distribution (correct)

    Correct. Counts of rare independent events over a period follow a Poisson distribution.

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, Poisson distribution. The Poisson distribution describes the number of rare, independent events occurring in a fixed interval of time or space with a constant average rate.

Why is "Uniform distribution" not the answer?

A uniform distribution gives equal probability to all outcomes, which does not fit rare events.

Why is "Normal distribution" not the answer?

The normal distribution models continuous measurements, not counts of rare events.

Why is "Student's t distribution" not the answer?

The t distribution is a sampling distribution for means, not for counts of events.

What concept does this question test?

It tests Biostatistics: Poisson distribution in PSM. The normal distribution is for continuous measurements that cluster around a mean. The t distribution is used for means of small samples.

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 Biostatistics: Poisson distribution?

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.