Biostatistics: Kruskal-Wallis test: 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: Kruskal-Wallis test

Sample item

Pain scores on a 0 to 10 ordinal scale, clearly skewed, are compared among three independent groups of patients who received three different analgesics. Which test is most appropriate?

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

The answer and the reasoning

C. Kruskal-Wallis test

The Kruskal-Wallis test is the non-parametric counterpart of one-way ANOVA and compares three or more independent groups on ordinal or non-normal data. The Friedman test is its equivalent for repeated measures in related groups.

Option by option

  • A. One-way analysis of variance

    One-way ANOVA assumes approximately normal, interval-scale data, which these scores do not satisfy.

  • B. Mann-Whitney U test

    The Mann-Whitney U test compares only two independent groups.

  • C. Kruskal-Wallis test (correct)

    Correct. It compares three or more independent groups when data are ordinal or skewed.

  • D. Friedman test

    The Friedman test is for three or more related measurements in the same subjects, not independent 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.

More PSM questions

Questions about this PSM question

What is the answer to this PSM question?

The best answer is C, Kruskal-Wallis test. The Kruskal-Wallis test is the non-parametric counterpart of one-way ANOVA and compares three or more independent groups on ordinal or non-normal data.

Why is "One-way analysis of variance" not the answer?

One-way ANOVA assumes approximately normal, interval-scale data, which these scores do not satisfy.

Why is "Mann-Whitney U test" not the answer?

The Mann-Whitney U test compares only two independent groups.

Why is "Friedman test" not the answer?

The Friedman test is for three or more related measurements in the same subjects, not independent groups.

What concept does this question test?

It tests Biostatistics: Kruskal-Wallis test in PSM. The Friedman test is its equivalent for repeated measures in related groups.

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: Kruskal-Wallis test?

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.