Biostatistics: confidence intervals: 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 intervals

Sample item

A study reports a relative risk of 1.8 with 95% confidence interval 1.2 to 2.7. What is the best interpretation?

AThe result proves causationBThe data are compatible with an increased risk and the interval excludes 1CThe exposure is protectiveDThere is no association because 1.8 is below 2

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

The answer and the reasoning

B. The data are compatible with an increased risk and the interval excludes 1

For ratio measures such as relative risk, a confidence interval excluding 1 suggests statistical incompatibility with no association at the stated confidence level. Association alone does not prove causation.

Option by option

A. The result proves causation
Causal inference also requires attention to bias, confounding, and design.
B. The data are compatible with an increased risk and the interval excludes 1 (correct)
Correct. The entire interval lies above 1, supporting increased risk.
C. The exposure is protective
A value above 1 indicates increased rather than protective association.
D. There is no association because 1.8 is below 2
A relative risk need not exceed 2 to be statistically meaningful.

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.

Questions about this PSM question

What is the answer to this PSM question?

The best answer is B, The data are compatible with an increased risk and the interval excludes 1. For ratio measures such as relative risk, a confidence interval excluding 1 suggests statistical incompatibility with no association at the stated confidence level.

Why is "The result proves causation" not the answer?

Causal inference also requires attention to bias, confounding, and design.

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

A value above 1 indicates increased rather than protective association.

Why is "There is no association because 1.8 is below 2" not the answer?

A relative risk need not exceed 2 to be statistically meaningful.

What concept does this question test?

It tests Biostatistics: confidence intervals in PSM. Association alone does not prove causation.

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: confidence intervals?

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.