The NICE glossary provides brief definitions and explanations of terms and jargon used on our site. The terms describe how we work and how our guidance is produced.

Our glossary excludes specific clinical and medical terms although we intend to include these in the longer term. If you cannot find the term you are looking for, please email us so that we can consider adding it to the glossary. New terms are added regularly.

The glossary is not used for indexing the site or for navigation - for information on this, please see the NICE taxonomy.

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



Data are the information collected through research. They can include written information, numbers, sounds and pictures.

Data set

A collection of data, usually presented in a table. Each column represents a particular variable. For example, the dataset from a survey of schoolchildren could be organised so that the data could easily be compared by the age and sex of respondents. The tables might then be summarised so that you could compare behaviour or illnesses experienced, grouped by the age and sex of each respondent.

Declaration of interest

NICE staff and members of any NICE working group or committee must make a declaration of interest if they have any personal or professional involvement with a company that might affect their objectivity. For example, they must declare an interest if their position or department is funded by a pharmaceutical company or another organisation providing products or services relevant to the committee's work.

Delphi method

A technique used to reach agreement on a particular issue without those involved meeting or having any direct contact. Participants are sent a series of postal questionnaires asking them to record their views. After the results of the first questionnaire are distributed, participants are asked to comment in light of the group feedback.


The study of a population, particularly its size, density, fertility, death rates, growth rates, age range, geographic distribution and migration.

Deprived areas

Geographic regions or areas that have significantly higher levels of unemployment and lower rates of income per head than the national average.

Determinants of health

The range of personal, social, economic and environmental factors that determine the health of people and communities. They include behaviours that can affect health (such as smoking), income, education, employment, working conditions, access to health services, housing and general living conditions.


A physical item or artificial body part (called a prosthesis) used to treat or diagnose a disease or condition. For example, a device might be a pacemaker, knee replacement, X-ray or blood pressure kit (but not a drug).


The process of identifying a disease or condition by carrying out tests or by studying the symptoms.

Diagnostic study

A study to assess the effectiveness of a test or measurement in detecting whether someone has (or does not have) a specific disease.

Directorate (see also Centre)

Directorates are departments in NICE that provide services across the whole of NICE:

  • the Communications Directorate, which publishes NICE guidance and communicates with health and other professionals, and the public
  • the Implementation Systems Directorate, which helps the NHS and other organisations put NICE guidance into practice
  • the Planning and Resources Directorate, which provides services such as finance, human resources and IT, so that NICE can work effectively
  • the Clinical and Public Health Directorate, which provides information services for NICE, supports the Citizens' Council and Partners' Council, and coordinates NICE's involvement in research.

Centres are the departments in NICE that produce specific types of guidance

Disability-adjusted life year

A measure of the impact of a disease or injury in terms of healthy years lost.


The active process of distributing information such as evidence or practice advice, to ensure maximum exposure to and uptake by relevant groups of people.


A health economics term. When comparing tests or treatments, an option that is both less effective and costs more is said to be 'dominated' by the alternative.

Double blind study

See blinding.

Double masked

See blinding.

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This page was last updated: 15 April 2011

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Selected, reliable information for health and social care in one place

Accessibility | Cymraeg | Freedom of information | Vision Impaired | Contact Us | Glossary | Data protection | Copyright | Disclaimer | Terms and conditions

Copyright 2014 National Institute for Health and Care Excellence. All rights reserved.