Biostatistics: type I error: 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: type I error

Sample item

What is a type I error in hypothesis testing?

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

The answer and the reasoning

B. Rejecting a true null hypothesis

A type I error is a false-positive conclusion: concluding there is an effect when the null hypothesis is true. The chosen alpha level sets the tolerated probability of this error under the model.

Option by option

  • A. Using a small sample

    Small samples can affect power but are not themselves type I error.

  • B. Rejecting a true null hypothesis (correct)

    Correct. This is the definition of a false positive in hypothesis testing.

  • C. Calculating a median incorrectly

    Calculation mistakes are not the statistical definition.

  • D. Failing to reject a false null hypothesis

    Failing to reject a false null is a type II 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.

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Questions about this PSM question

What is the answer to this PSM question?

The best answer is B, Rejecting a true null hypothesis. A type I error is a false-positive conclusion: concluding there is an effect when the null hypothesis is true.

Why is "Using a small sample" not the answer?

Small samples can affect power but are not themselves type I error.

Why is "Calculating a median incorrectly" not the answer?

Calculation mistakes are not the statistical definition.

Why is "Failing to reject a false null hypothesis" not the answer?

Failing to reject a false null is a type II error.

What concept does this question test?

It tests Biostatistics: type I error in PSM. The chosen alpha level sets the tolerated probability of this error under the model.

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: type I error?

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.