What is the purpose of blinding in clinical studies?

• A. To reveal treatment allocation to investigators
• B. To conceal information about the intervention from participants
• C. To increase observable outcomes
• D. To ensure all participants receive the same care

Answer: (B)

Blinding helps prevent bias in how people experience, report, and assess outcomes. When participants don’t know which treatment they’re receiving, their expectations or beliefs about benefit can influence their reporting of symptoms or adherence, reducing placebo effects. If investigators or outcome assessors also don’t know the treatment assignments, their measurements and judgments are less likely to be influenced by expectations. This combination keeps observed differences more likely due to the actual intervention rather than subjective influence. So concealing information about the intervention from participants is a core way blinding reduces bias and improves the trial’s validity.