Biostatistics: 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 · Biostatistics

Sample item

If the sample size in a study is increased fourfold with the same standard deviation, what happens to the standard error of the mean?

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

The answer and the reasoning

B. It is halved

Standard error of the mean equals standard deviation divided by the square root of n. Quadrupling n multiplies the denominator by two, so the standard error halves.

Option by option

  • A. It falls to one-third

    One-third does not follow from the square-root relationship.

  • B. It is halved (correct)

    The root of four is two, so the standard error falls to half.

  • C. It is quartered

    It would fall to a quarter only if it varied inversely with n rather than with its square root.

  • D. It does not change

    Sample size directly affects the standard error.

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 B, It is halved. Standard error of the mean equals standard deviation divided by the square root of n.

Why is "It falls to one-third" not the answer?

One-third does not follow from the square-root relationship.

Why is "It is quartered" not the answer?

It would fall to a quarter only if it varied inversely with n rather than with its square root.

Why is "It does not change" not the answer?

Sample size directly affects the standard error.

What concept does this question test?

It tests Biostatistics in PSM. Quadrupling n multiplies the denominator by two, so the standard error halves.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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?

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.