This type of bias can be assessed by a funnel plot. Quality of life See Health-related quality of life . Quality-adjusted life year (QALY) A measure of the state of health of a person or group in which the benefits, in terms of length of life, are adjusted to reflect the quality of life. One QALY is equal to 1 year of life in perfect health. QALYS are calculated by estimating the years of life remaining for a patient following a particular treatment or intervention and weighting each year with a quality of life score (on a scale of 0 to 1). It is often measured in terms of the person s ability to perform the activities of daily life, freedom from pain and mental disturbance. Randomisation Assigning participants in a research study to different groups without Chronic Heart Failure Glossary NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 Term Definition taking any similarities or differences between them into account. For example, it could involve using a random numbers table or a computer- generated random sequence. It means that each individual (or each group in the case of cluster randomisation) has the same chance of receiving each intervention. Randomised controlled trial (RCT) A study in which a number of similar people are randomly assigned to 2 (or more) groups to test a specific drug or treatment. One group (the experimental group) receives the treatment being tested, the other (the comparison or control group) receives an alternative treatment, a dummy treatment (placebo) or no treatment at all. The groups are followed up to see how effective the experimental treatment was. Outcomes are measured at specific times and any difference in response between the groups is assessed statistically. This method is also used to reduce bias. 