What does it meant to say that a study is "double-blind"?

Question

Quizplus · Accepted Answer

In a double-blind study, both the patient receiving the treatment and the evaluator do not know which group the patient belongs to (treatment or placebo). This controls for bias and ensures more accurate results. Option A describes a crossover study design. Option B describes a single-blind study. Option D describes a two-group design, but does not necessarily indicate that the study is double-blind.

What Does It Meant to Say That a Study Is