12.9:
Blinding
Blinding is an essential component of randomized control trials to reduce bias and increase the validity of the outcomes. It hides treatment information for patients, physicians, data analysts, and other personnel involved in the trial.
Randomized control trials use a placebo to achieve blinding. The placebo effect is a psychological phenomenon where an untreated subject may falsely believe that they have received the actual treatment and report improved symptoms. So, to reduce this bias, a placebo or a dummy treatment is given along with the test treatment.
In clinical trials, single, double, and triple blinding are commonly used.
In single-blind techniques, patients don't know whether they have received a placebo or the actual treatment.
Double-blind research hides the treatment information from both – the patient and the physician. As a result, there will be no false information from patients or physicians who might be in favor of the treatment and report biased observations.
A triple-blind study hides treatment information from patients, physicians, and data analysts.
12.9:
Blinding
Blinding is a commonly used method of not telling participants which treatment a subject is receiving. Blinding is a critical part of a randomized control trial or RCT. It reduces the bias that affects the results. In an RCT, blinding is used in the form of a placebo. A placebo effect occurs when untreated subjects falsely believe they have received the treatment and report improved symptoms. A placebo or a dummy treatment is administered to subjects to negate the bias caused by such an effect.
When participation in a study prompts a physical response from a participant, it is difficult to isolate the effects of the explanatory variable. To counter the power of suggestion, researchers set aside one treatment group as a control group. This group is given a placebo treatment–a treatment that cannot influence the response variable. The control group helps researchers balance the effects of being in an experiment with the effects of the active treatments. Of course, if you are participating in a study and you know that you are receiving a pill that contains no actual medication, then the power of suggestion is no longer a factor. Blinding in a randomized experiment preserves the power of suggestion. When a person involved in a research study is blinded, he does not know who is receiving the active treatment(s) and who is receiving the placebo treatment. A double-blind experiment is one in which both the subjects and the researchers involved with the subjects are blinded.
Blinding can be done on all the people involved in the clinical trials – subjects, clinicians, data collectors, outcome adjudicators, and data analysts.
This text is adapted from Openstax, Introductory Statistics, Section 1.4, Experimental Design and Ethics