Blinding is when researchers, clinical trial participants, or both don't know who is receiving which treatment until near the end of the trial.
Knowing a participant’s treatment can affect some health measurements. This is called bias and can affect the results. Blinding helps avoid bias in clinical trials.
Blinding can be:
– single blind, where participants don’t know which treatment they are getting, but the researchers know
– double blind, where the participants and the researchers don’t know who is receiving which treatment
At the end of the trial, researchers find out know who received which treatment. Participants can also find out which treatment they received. The researchers then analyse the results to see if the new treatment is safe and improves health.