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.

  • DALY

    See Disability-adjusted life year

  • Data

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

    The process of fixing or removing incorrect, duplicate, corrupt or inaccurate records in a dataset.

  • Data controller

    Organisation which determines when and how data can be processed. A data controller may not necessarily access or process the data themselves.

  • Data curation

    The process of preparing data for analysis including data linkage, cleaning, transformation and selection.

  • Data dictionary

    A description of the contents, format and structure of a dataset.

  • Data element

    A piece of structured information in a dataset such as age.

  • Data governance

    Data governance includes the policies and procedures used to ensure that data input is accurate, and that data is then stored, manipulated, accessed and deleted appropriately.

  • Data linkage

    Process of combining sources of data for a single individual (or other entity). Linkage can be deterministic or probabilistic. Deterministic linkage typically makes use of a pre-determined set of rules for classifying pairs of records as belonging to the same individual or not. Probabilistic linkage methods work by assigning a match weight to represent the likelihood that two records belong to the same individual.

  • Data model

    A representation of the data elements in a data source and how they relate to each other.

  • Data pooling

    Process of combining sources of data on different individuals. It is often used to increase sample size especially in rare diseases.

  • Data provenance

    Describes the ability to trace the origin of data and identify how it has been altered and transformed throughout its lifecycle. It provides an understanding of the trustworthiness or reliability of a data source.

  • 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.
  • Data transformation

    Process of changing the format, structure or values of data to make it ready for analysis.

  • Decision problem

    The decision problem describes the proposed approach to be taken in a sponsor’s submission of evidence to answer the question in a scope. This includes the population, intervention, comparator(s), outcomes, cost analysis, subgroup analysis and any special considerations.

  • Decision-analytic model (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 reaching agreement on a particular issue, without the people involved meeting or interacting directly. It involves sending those involved a series of questionnaires asking their views. After completing each questionnaire, they are asked to give further views in the light of the group feedback until the group reaches a predetermined level of agreement. The judgements of those involved may be analysed statistically. 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.
  • Development team

    A team that develops guidance in a particular topic area. Technical staff identify and review the evidence, and project staff recruit and manage the committee.

  • Device

    A piece of equipment used for diagnostic or therapeutic purposes, sometimes along with (a) pharmaceutical agent(s).

  • 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 Assessment Programme

    Focuses on the evaluation of innovative medical diagnostic technologies to make sure that the NHS is able to adopt clinically- and cost-effective technologies rapidly and consistently.

  • Diagnostics assessment report

    A report prepared by the external assessment group, based on a systematic review of the clinical and health economic literature, and modelling as appropriate to estimate health outcomes and cost effectiveness.

  • 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.
  • Digital media

    Digital media interventions are technology-based and interactive. They include internet and mobile-phone based interventions. Internet interventions can include real-time streaming of information and podcasts, discussions with experts and social networking sites.

  • 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.

    If several tests or treatments are compared and the ICER for one is higher than that of the next, more effective, option when compared with a common baseline, it is said to be extendedly dominated.

  • Double-blind study

    See Blinding or masking

  • Draft guidance

    Draft guidance summarises the evidence and views considered by the committee. It describes preliminary recommendations. It is not NICE’s final guidance on a technology and the recommendations may change after consultation.