Randomised controlled trial
These is a test where groups of people are randomly divided and given different types of treatment, then monitored to see the difference between the two. This can help to understand what treatments are best or what treatments are harmful. Randomised controlled trials can be 'single blind' (where the participant doesn’t know what treatment they are having) or double blind (where neither the participant nor the researcher knows what treatment is being used). These are usually the most reliable types of trial.
This is a way to describe chance, measured in proportion to another chance. For example, a drug might cut the risk of a heart attack by 50%. To understand what this means for us, we have to know what our risk was to start with. So, for example, if we had a risk of a heart attack of 60%, the drug could cut the risk to 30% (half of 60%). But if we had a risk of 2%, the drug would cut the risk to 1% (half of 2%).