In a meta-analysis, the funnel plot shows marked asymmetry, with smaller studies clustered away from the pooled effect line on one side. The most appropriate interpretation is:
- A High statistical heterogeneity requiring a random-effects model
- B Excessive weighting of large trials
- C Likely publication bias or small-study effects ✓
- D Failure of randomization in individual trials
Correct answer: C. Likely publication bias or small-study effects
Explanation
In a symmetric funnel plot, precision increases with sample size, so points scatter evenly around the pooled estimate. Asymmetry suggests smaller negative or null trials went unpublished, or that small studies exaggerate effects through methodological shortcomings, together termed small-study effects. Heterogeneity refers to spread of true effect sizes between studies and is quantified by I-squared, not assessed visually by funnel plot shape.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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