A cohort study of factory workers finds lower all-cause mortality than the general population. The most likely explanation is that working populations must be comparatively fit to gain and hold employment. This phenomenon is known as:

• A Berkson's bias
• B Hawthorne effect
• C Neyman's bias
• D Healthy worker effect ✓

Explanation

The healthy worker effect is a form of selection bias seen in occupational cohorts: employed people are systematically healthier than the general population, which includes the chronically ill and unemployed, so their mortality appears spuriously low. Berkson's bias arises from hospital-based sampling, Neyman's bias from excluding prevalent cases who died or recovered, and the Hawthorne effect is altered behaviour under observation.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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