Biostatistics: confidence interval of relative risk: 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: confidence interval of relative risk

Sample item

A cohort study reports a relative risk of 1.4 with a 95 percent confidence interval of 0.9 to 2.1. What is the correct interpretation?

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

The answer and the reasoning

A. The association is not statistically significant at the 5 percent level

A confidence interval for RR that includes 1 indicates that no association cannot be excluded, so the result is not statistically significant at the 5 percent level. The point estimate alone does not prove harm.

Option by option

  • A. The association is not statistically significant at the 5 percent level (correct)

    Correct. The interval includes 1, so it is not significant.

  • B. The exposure is significantly harmful

    Significant harm requires the whole interval above 1.

  • C. The study has no bias

    The confidence interval says nothing about bias.

  • D. The exposure is significantly protective

    Significant protection requires the whole interval below 1.

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 A, The association is not statistically significant at the 5 percent level. A confidence interval for RR that includes 1 indicates that no association cannot be excluded, so the result is not statistically significant at the 5 percent level.

Why is "The exposure is significantly harmful" not the answer?

Significant harm requires the whole interval above 1.

Why is "The study has no bias" not the answer?

The confidence interval says nothing about bias.

Why is "The exposure is significantly protective" not the answer?

Significant protection requires the whole interval below 1.

What concept does this question test?

It tests Biostatistics: confidence interval of relative risk in PSM. The point estimate alone does not prove harm.

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: confidence interval of relative risk?

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.