Randomisation
You may have noticed some important concepts in the animation above. For instance, it explained that a computer, not a doctor or scientist, actually decides, at random, which treatment patients receive. This is called randomisation. We need randomisation in trials to avoid ‘systematic error’ or ‘bias’ (see below). If it was left to a human being to decide who was to get the treatment and who was not, they may, consciously or unconsciously, give the treatment to the people they think it will work best for. Or they might discriminate in other ways. Assigning people randomly by a computer will ensure that bias is not built into the design of the trial.