Biostatistics: interquartile range: 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: interquartile range

Sample item

Which measure of dispersion is least affected by extreme outliers?

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

The answer and the reasoning

B. Interquartile range

The interquartile range is the difference between the 75th and 25th percentiles and ignores extreme values. Range, SD and variance use extreme or all values and are sensitive to outliers.

Option by option

  • A. Variance

    Variance is the squared SD and equally sensitive.

  • B. Interquartile range (correct)

    Correct. IQR uses only the middle half of the data.

  • C. Standard deviation

    SD is influenced by every value, especially outliers.

  • D. Range

    Range depends entirely on the two extreme values.

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, Interquartile range. The interquartile range is the difference between the 75th and 25th percentiles and ignores extreme values.

Why is "Variance" not the answer?

Variance is the squared SD and equally sensitive.

Why is "Standard deviation" not the answer?

SD is influenced by every value, especially outliers.

Why is "Range" not the answer?

Range depends entirely on the two extreme values.

What concept does this question test?

It tests Biostatistics: interquartile range in PSM. Range, SD and variance use extreme or all values and are sensitive to outliers.

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: interquartile range?

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.