The NICE glossary provides brief definitions and explanations of terms used on the website. The terms describe how NICE works and how its guidance is produced.

Our glossary excludes specific clinical and medical terms. If you cannot find the term you are looking for, please email us so that we can consider adding it to the glossary.

Some definitions and examples are based on those in the HTAi consumer and patient glossary, with thanks to Health Technology Assessment International.

For terms used in social care, the Care and Support Jargon Buster from Think Local Act Personal is a useful guide to the most commonly used social care words and phrases, and what they mean.

  • Back-up prescription

    A back-up (delayed) prescription is one that is given in a way to delay the use of a medicine (usually an antibiotic), and with advice to only use it if symptoms worsen or don’t improve within a specified time. The prescription may be given during the consultation (which may be a post-dated prescription) or left at an agreed location for collection at a later date.

  • Baseline

    The set of measurements at the beginning of a study (after any initial 'run-in' period with no intervention), with which subsequent results are compared.

  • Before-and-after studies

    An approach in which dependent variables are measured before and after an intervention has been delivered. Often called a pre–post study. The people in the pre- and post-intervention stages can either be the same or different.

  • Benchmark

    A measure or standard that can be used to compare an activity, performance, service or result. 'Benchmarking' is the process of measuring the performance of people or organisations with broadly similar characteristics. The aim is to improve quality by encouraging all organisations or services to raise their own performance to that of the best.
  • Best available evidence

    The strongest, best-quality research evidence available on the topic being investigated.
  • Bias

    Systematic (as opposed to random) deviation of the results of a study from the 'true' results, which is caused by the way the study is designed or conducted.
  • Blinding or masking

    A way to prevent researchers, doctors and patients in a clinical trial from knowing which study group each patient is in so they cannot influence the results. The best way to do this is by sorting patients into study groups randomly. The purpose of 'blinding' or 'masking' is to protect against bias.
    In a single-blind study, patients do not know which study group they are in (for example whether they are taking the experimental drug or a placebo). In a double-blind study, neither the patients nor the researchers/doctors know which study group the patients are in. In a triple-blind study, the patients, clinicians and the people carrying out the statistical analysis do not know which treatment patients had.