Which practice helps minimize bias by keeping people unaware of group assignment?

Which practice helps minimize bias by keeping people unaware of group assignment?

• A. Randomization
• B. Blinding or masking
• C. Placebo control
• D. Stratification

Answer: (B)

Blinding or masking prevents bias by keeping participants and, sometimes, investigators unaware of which intervention a person receives. When people don’t know their group, their expectations and beliefs are less likely to influence how they report symptoms, adhere to protocols, or how outcomes are assessed. This reduces placebo effects, observer bias, and detection bias, leading to a more accurate estimate of the intervention’s true effect. While randomization helps create comparable groups, it doesn’t automatically hide assignment. A placebo control provides a neutral comparison but doesn’t inherently conceal who is in which group. Stratification ensures balance on certain characteristics but doesn’t address bias from knowledge of treatment. Blinding directly minimizes bias arising from awareness of group assignment.

Blinding or masking prevents bias by keeping participants and, sometimes, investigators unaware of which intervention a person receives. When people don’t know their group, their expectations and beliefs are less likely to influence how they report symptoms, adhere to protocols, or how outcomes are assessed. This reduces placebo effects, observer bias, and detection bias, leading to a more accurate estimate of the intervention’s true effect. While randomization helps create comparable groups, it doesn’t automatically hide assignment. A placebo control provides a neutral comparison but doesn’t inherently conceal who is in which group. Stratification ensures balance on certain characteristics but doesn’t address bias from knowledge of treatment. Blinding directly minimizes bias arising from awareness of group assignment.