A fair and unbiased test of whether a treatment works. Randomised controlled trials (also called randomised trials, controlled trials and clinical trials) provide the best evidence about the benefits and risks of treatments.The people taking part in the trial are put into different groups at random. They are usually selected for each group by a computer. One group, the intervention group receives the treatment being tested and the other is the control group. The control group gets the most widely-accepted current treatment, called the standard treatment.