The NICE Glossary provides brief definitions and explanations of terms used on our site. The terms describe how we work and how our 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.

  • Data

    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.
  • Decision problem

    The decision problem describes the proposed approach to be taken in the sponsor's submission of evidence to answer the question in the scope. This includes the population, intervention, comparator(s), outcomes, cost analysis, subgroup analysis and any special considerations.
  • Decision-analytic model (and/or technique)

    A model of how decisions are or should be made. This could be one of several models or techniques used to help people to make better decisions (for example, when considering the trade-off between costs, benefits and harms of diagnostic tests or interventions).
  • 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 in their work for NICE. 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 for the purpose of reaching an agreement on a particular issue, without the participants meeting or interacting directly. It involves sending participants a series of postal questionnaires asking them to record their views. After the first questionnaire, participants are asked to give further views in the light of the group feedback. The judgements of the participants are statistically aggregated, sometimes after weighting for expertise. See also Consensus methods.
  • Demography

    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.
  • Diagnosis

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

    The independent committee that develops NICE's guidance on new medical technologies that can be used to help diagnose or investigate a disease or condition (diagnostics).
  • Diagnostics guidance

    NICE guidance on new medical technologies that can be used to help diagnose or investigate a disease or condition (diagnostics). It aims to ensure that the NHS is able to adopt tests that are clinically and cost effective more rapidly and consistently.
  • Disability-adjusted life year

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

    Costs and perhaps benefits incurred today have a higher value than costs and benefits occurring in the future. Discounting health benefits reflects individual preference for benefits to be experienced in the present rather than the future. Discounting costs reflects individual preference for costs to be experienced in the future rather than the present.
  • Discrete event simulation

    A method that can be used to model the course of a disease (for example, to predict disease progression for the purposes of cost-effectiveness analysis).
  • Dominance

    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.
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