What does “blinding” mean?


Blinding means that whoever is assessing the effects of treatment will not know if they are studying patients on the treatment or patients on placebo. This helps to prevent bias. Sometimes patients will assess the effects of treatment, sometimes doctors will, and sometimes third parties will. Some or all of these people may be kept unaware of which treatment has been received. If you are part of a 'single blind' trial you will not know which treatment you are receiving. If you take part in a 'double-blind' trial, neither you nor your doctor will know which treatment you are receiving. The aim is to make sure that nobody's expectations affect the results of the trial.