Biostatistics: comparing survival curves: 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: comparing survival curves

Sample item

Two treatments for oral cancer are compared in a follow-up study. Some patients are lost to follow-up and are censored. Which test is used to compare the survival curves of the two groups?

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

The answer and the reasoning

B. Log-rank test

Survival curves estimated by the Kaplan-Meier method are compared with the log-rank test, which uses the whole time course of events and accommodates censored data. A paired t-test compares paired means, and Pearson correlation measures linear association of two quantitative variables.

Option by option

  • A. Chi-square test for trend

    A chi-square test for trend examines ordered categories and ignores time to event and censoring.

  • B. Log-rank test (correct)

    Correct. The log-rank test compares time-to-event distributions with censoring.

  • C. Paired t-test

    A paired t-test compares mean differences in matched or before-after measurements.

  • D. Pearson correlation coefficient

    Pearson correlation quantifies association between two continuous variables and does not compare groups.

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, Log-rank test. Survival curves estimated by the Kaplan-Meier method are compared with the log-rank test, which uses the whole time course of events and accommodates censored data.

Why is "Chi-square test for trend" not the answer?

A chi-square test for trend examines ordered categories and ignores time to event and censoring.

Why is "Paired t-test" not the answer?

A paired t-test compares mean differences in matched or before-after measurements.

Why is "Pearson correlation coefficient" not the answer?

Pearson correlation quantifies association between two continuous variables and does not compare groups.

What concept does this question test?

It tests Biostatistics: comparing survival curves in PSM. A paired t-test compares paired means, and Pearson correlation measures linear association of two quantitative variables.

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: comparing survival curves?

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.