Randomised controlled studies make fair comparisons between two groups of people, one of which (the control group) received standard care, and the other (the experimental group) receives a treatment in addition to standard care.
It is important that in these studies, the two groups of people are as similar as possible, except for the treatment they receive. This matters because it makes sure that any differences in outcomes between the two groups are only due to the treatment received.
The decision about which treatment each participant in a randomised controlled study receives is made at random, rather than decided by the doctor or participant. This process is called randomisation.
Randomisation is the best way of ensuring that the results of studies are not biased by the way people in each group are selected.
Randomised controlled studies are the most reliable way to compare treatments.
Clinical trial resources
These resources provide more video, audio, and written information about clinical trials:
Medical Research Council video
Testing Treatments
Promoting critical thinking about treatment claims.
Testing Treatments interactive
Healthtalk videos about clinical trials
Find out about the experience of taking part in a clinical trial by listening to people share their personal stories on film.
Be Part of Research
You can find out more about taking part in health research in the UK via National Institute for Health and Care Research (NIHR) Be Part of Research.