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The concealment of group assignment—to either the treatment or control group—from the knowledge of patients and/or investigators in a clinical trial of whether a drug or therapy being administered is a placebo/sham treatment—i.e., the control group—or the drug/treatment being investigated


Clinical research The concealment of group assignment–to either the treatment or control group from the knowledge of Pts and/or investigators in a clinical trial; while blinding is intended to remove bias and subjectivity, it is not always practical–eg when comparing surgery to drug treatment, but should be used when possible and compatible with optimal Pt care. See Double blinded study, 'Nocebo. ', Placebo, Triple blinded study. Cf Control.


n within a clinical trial, hiding the knowledge of a particular treatment. The three types of blinding are the following: observer-blind—when the researcher does not know the particular treatment that a patient undergoes; single-blind, when only the patient does not know to which group he or she belongs; and double-blind, when both the patient and the one providing the treatment do not know group identity. These types of blinding ensure—all other factors being identical—that any observed results are not the result of bias of the study participants.


a condition imposed on a study which is intended to keep knowledge of the treatment assignment of individual patients from a specified set of observers. Used to reduce information bias. Single blind: the owner of the patient is unaware of the treatment assignment but the veterinarian is aware. Double blind: both the owner of the patient and the veterinarian are unaware of the treatment assignments of the patients. Triple blind: the owners of the patients, the veterinarian and the person analyzing the results of the study are all unaware of the treatment assignments. Called also masking.

Patient discussion about blinding

Q. Why is the color draining from my eyes?! When I was little I had rich shiny cobalt blue eyes! As I grew up they faded or just started to dim in color. Being partially blind you can see in my left eye the its a really light color and creamy instead of my deep blue color... Why does my eye color dim?! I didnt think going blind had anything to do with the color of my eyes changing... Or is it something else?! Please, and thank you!

A. depends on your blindness, if it is caused by your cornea changing (corneal opacity)- it'll change your eye color to a cloudy white. it can also be caused by cataract.
are those the reason of your blindness?

More discussions about blinding
References in classic literature ?
As soon as he had finished his horrible repast he lay down to sleep as before, and when we heard him begin to snore I, and nine of the boldest of my comrades, rose softly, and took each a spit, which we made red-hot in the fire, and then at a given signal we plunged it with one accord into the giant's eye, completely blinding him.
Give me something to wipe myself with, if thou hast it, for this profuse sweat is blinding me.
The wind aided him in this, and soon there arose a blinding cloud which filled the eyes, noses, and mouths of the three outlaws till they could scarcely see or breathe.
Finally Zad, realizing that he was tiring more than I, evidently decided to close in and end the battle in a final blaze of glory for himself; just as he rushed me a blinding flash of light struck full in my eyes, so that I could not see his approach and could only leap blindly to one side in an effort to escape the mighty blade that it seemed I could already feel in my vitals.