In a study comparing two treatments for hypertension, the investigators did not know which treatment each patient received. This design element is called:

• A Randomization
• B Matching
• C Stratification
• D Blinding ✓

Explanation

Blinding (masking) prevents knowledge of treatment allocation from influencing assessment or behavior. If investigators are unaware of treatment assignment, it is single-blind; if both participants and investigators are unaware, it is double-blind. Blinding minimizes performance bias and detection bias. Randomization ensures comparable groups at baseline but is distinct from blinding.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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