A case-control study on oral contraceptive use and hepatic adenoma is conducted. Cases are recruited from hepatology clinics and controls from the same hospital's orthopedic wards. Women with known liver disease are excluded from both groups. This control selection is most likely to introduce which type of bias?
- A Berkson's bias ✓
- B Neyman (incidence-prevalence) bias
- C Hawthorne effect
- D Ecological fallacy
Correct answer: A. Berkson's bias
Explanation
Berkson's bias (hospital admission bias) occurs in hospital-based case-control studies when controls selected from the same hospital have different exposure rates than the general population, because hospital patients are a non-random sample. Orthopedic patients may have different OCP use patterns than the general community. Neyman bias relates to excluding early fatal or rapidly resolving cases. Hawthorne effect is a form of observer bias. Ecological fallacy arises when group-level associations are applied to individuals.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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