Why, in Clinical Trails, are they Blind? [Placebo Stage]

-This is in order for the Patient to not know if they are getting the Drug, or the Placebo - it may even be that the Scientist is Blind, so they don't know who has the Placebo or the Medicine -This allows the Results to not be Influenced by the Patients Knowing they will receive the Fake, or the Real - or for the Scientist to not give out Obvious Cues