Epidemiology: heterogeneity in meta-analysis: 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 · Epidemiology: heterogeneity in meta-analysis

Sample item

In a forest plot of trials of a vaccine, the I-squared statistic is 85 percent. What is the appropriate interpretation?

AThe studies are homogeneous and fixed-effect pooling is idealBStrong evidence of publication biasCThe pooled estimate is statistically significantDSubstantial between-study heterogeneity, so explore its causes or use a random-effects model

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

The answer and the reasoning

D. Substantial between-study heterogeneity, so explore its causes or use a random-effects model

I-squared estimates the proportion of variability between studies that is due to real differences rather than chance. A value of 85 percent indicates considerable heterogeneity, so the reasons should be explored and a random-effects model considered. It says nothing about publication bias or significance.

Option by option

A. The studies are homogeneous and fixed-effect pooling is ideal
A high value indicates the opposite of homogeneity.
B. Strong evidence of publication bias
Publication bias is assessed with a funnel plot, not I-squared.
C. The pooled estimate is statistically significant
Significance of the pooled effect is judged from its confidence interval.
D. Substantial between-study heterogeneity, so explore its causes or use a random-effects model (correct)
Correct. A high I-squared signals marked between-study differences.

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 D, Substantial between-study heterogeneity, so explore its causes or use a random-effects model. I-squared estimates the proportion of variability between studies that is due to real differences rather than chance.

Why is "The studies are homogeneous and fixed-effect pooling is ideal" not the answer?

A high value indicates the opposite of homogeneity.

Why is "Strong evidence of publication bias" not the answer?

Publication bias is assessed with a funnel plot, not I-squared.

Why is "The pooled estimate is statistically significant" not the answer?

Significance of the pooled effect is judged from its confidence interval.

What concept does this question test?

It tests Epidemiology: heterogeneity in meta-analysis in PSM. A value of 85 percent indicates considerable heterogeneity, so the reasons should be explored and a random-effects model considered. It says nothing about publication bias or significance.

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 Epidemiology: heterogeneity in meta-analysis?

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.