What is the role of blinding in reducing bias in study design?

• A. Blinding increases sample size.
• B. Blinding eliminates all bias.
• C. Blinding replaces randomization.
• D. Blinding reduces bias in data collection/measurement.

Answer: (D)

Blinding helps prevent bias by keeping those who collect and assess outcome data unaware of which treatment a participant received, so measurements and judgments aren’t influenced by expectations. This reduces detection and measurement bias, and, depending on who is blinded, can limit other biases related to how participants behave or report outcomes. Blinding doesn’t change the number of participants, it doesn’t eliminate all bias, and it doesn’t replace randomization, which aims to balance confounders across groups.