A systematic review uses Funnel plot asymmetry to assess potential bias. An asymmetric funnel plot with absence of studies in the lower left quadrant MOST suggests:
- A Heterogeneity among included studies
- B Overestimation of the true effect by all studies
- C Publication bias favouring positive results ✓
- D Inadequate blinding in included trials
Correct answer: C. Publication bias favouring positive results
Explanation
A funnel plot plots study effect size (x-axis) against precision or sample size (y-axis). Symmetry is expected if there is no systematic bias. Missing studies in the lower left (small, negative studies) suggest publication bias, wherein small studies with non-significant or negative results are not published. This asymmetry inflates the pooled effect estimate in meta-analysis.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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