Process and methods

Glossary of terms

Glossary of terms

Please see the NICE glossary for explanations of terms not described in the table below. Additional terms may be found in The guidelines manual: appendix L2 glossary. A glossary may be added to a specific good practice guidance if needed, to provide clarity and understanding of the guidance.


Summary of a study, which may be published alone or as an introduction to a full scientific paper.

AGREE (appraisal of guidelines research and evaluation)

An international collaboration of researchers and policy makers whose aim is to improve the quality and effectiveness of clinical practice guidelines. The AGREE II instrument, developed by the group, is designed to assess the quality of clinical guidelines.

Algorithm in guidance

A flow chart of the decision pathway described in the guidance, where decision points are represented by boxes, linked with arrows.


The degree to which the results of an observation, study or review are likely to hold true in a particular practice setting.

Arm (of a clinical study)

Subsection of participants within a study who receive 1 particular intervention (for example, the placebo arm).


Statistical relationship between 2 or more events, characteristics or other variables. The relationship may or may not be causal.

Audit support

The provision of ready-to-use criteria, including exceptions, definitions and data source suggestions, in order to make the process of developing clinical audit projects easier. NICE provides audit support for good practice guidance where appropriate.

Audit trail

Records of action to assess practice against standards. Also a record of actions (for example, changes to draft guidance) so that the reasons are apparent to a third party.


The initial set of measurements at the beginning of a study (after the period before the study starts when no treatment is given [the 'run‑in' period], where applicable), with which subsequent results are compared.


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.

Centre for Clinical Practice (CCP)

The department at NICE that manages the development of good practice guidance.

Clinical effectiveness

The extent to which an intervention produces an overall health benefit in routine clinical practice.

Cochrane Review

A systematic review of the evidence from randomised controlled trials relating to a particular health problem or healthcare intervention, produced by the Cochrane Collaboration. Available electronically as part of the Cochrane Library.

Code of conduct (of the GDG)

A code of conduct developed by NICE for Guidance Development Group (GDG) members and other people who attend GDG meetings. This code sets out the responsibilities of NICE and the GDG, and the principles of transparency and confidentiality.


Similarity of groups in terms of characteristics likely to affect study results (such as health status or age).


The standard intervention against which an intervention is compared in a study. The comparator can be no intervention (for example, best supportive care).

Conceptual framework

A theoretical structure of assumptions, principles and rules that holds together the ideas comprising a broad concept.

Conceptual model

A descriptive model of a system based on qualitative assumptions about its elements, their interrelationships, and system boundaries.

Conflict of interest

An interest that might conflict, or be perceived to conflict, with duties and responsibilities to an organisation.


In a study, confounding occurs when the effect of an intervention on an outcome is distorted as a result of an association between the population or intervention or outcome and another factor (the 'confounding variable' or 'confounder') that can influence the outcome independently of the intervention under investigation.

For example, a study of heart disease may look at a group of people that exercises regularly and a group that does not exercise. If the ages of the people in the 2 groups are different, then any difference in heart disease rates between the 2 groups could be because of age rather than exercise. Therefore age is a confounding factor.

Consensus methods

Techniques that aim to reach an agreement on a particular issue. Formal consensus methods include Delphi and nominal group techniques, and consensus development conferences. In the development of clinical guidelines, consensus methods may be used when there is a lack of strong research evidence on a particular topic.

Consort diagram

Diagram showing the flow of steps or stages within a process


An explicitly defined comparator against which the effects of an intervention are compared in a clinical study.

Decision-analytic model (and/or technique)

A model of how decisions are or should be made. This could be 1 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).

Delphi technique

A technique used for reaching agreement on a particular issue, without the participants meeting or interacting directly. It involves sending participants a series of 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 may be statistically aggregated.


The prescribed amount of a drug to be taken, including the size and timing of the doses.


Fair distribution of resources or benefits.


Information on which a decision or guidance is based. Evidence is obtained from a range of sources, including randomised controlled trials, observational studies and expert opinion (of healthcare and other professionals and/or patients).

Evidence profile

A table summarising, for each important clinical outcome, the quality of the evidence and the outcome data (part of the GRADE approach).

Exceptional update

Review of existing guidance carried out sooner than originally planned because new data have become available.

Exclusion criteria (literature review)

Explicit standards used to decide which studies should be excluded from consideration as potential sources of evidence.

Expert consensus

See 'Consensus methods'.


In data analysis, predicting the value of a parameter outside the range of observed values.


Observation over a period of time of a person, group or initially defined population whose characteristics have been assessed in order to observe changes in health status or health-related variables.


The extent to which the results of a study based on measurement in a particular patient population and/or a specific context hold true for another population and/or in a different context.

Generic name

The general non-proprietary name of a drug or device.

Good practice guidance

Guidance and recommendations for good practice for those involved in governing, commissioning, prescribing and decision-making about medicines.

(Grading of recommendations assessment, development and evaluation)

A systematic and explicit approach to grading the quality of evidence and the strength of recommendations.

Grading (of evidence)

A code given to a study or other evidence, indicating its quality.

Consultation comments table

A table of all the comments received by NICE during guidance consultation. The Guidance Development Group considers the comments received, and the NICE project team then responds to the comments in the table.

Guidance Development Group (GDG)

A group of health and social care and other professionals, patients and carers, and technical staff who develop the recommendations for good practice guidance. The NICE project team responsible for developing the good practice guidance recruits a GDG to work on the guidance. The NICE project team reviews the evidence and support the GDG. The GDG writes draft guidance, and then revises it after a consultation with stakeholders.

Health, social care (and other) professional member

A member of the Guidance Development Group with appropriate knowledge and skills to represent the perspective(s) of the health and social care professionals (and other professionals where relevant) involved in the care of patients affected by the guidance topic.

Health economist

One of the teams within NICE, with skills in economic analysis, the role of which is to advise on economic aspects of the clinical issues or questions, review economic literature, prioritise topics for further analysis and carry out additional cost-effectiveness analyses. (Not all good practice guidance will require a health economist.)

Health inequalities

The gap in health status and in access to health services between different social classes and ethnic groups, and between populations in different geographical areas. For more information, see the Department of Health website.

Health-related quality of life

A combination of a person's physical, mental and social wellbeing; not merely the absence of disease.


An unproven theory that can be tested by research.


The process of putting guidance into practice.

Inclusion criteria (literature review)

Explicit criteria used to decide which studies should be considered as potential sources of evidence.

In confidence material

Information (for example, the findings of a research project) defined as 'confidential' because its public disclosure could have an impact on the commercial interests of a particular company ('commercial in confidence') or the academic interests of a research or professional organisation ('academic in confidence').

Indication (specific)

The defined use of a technology as licensed by the Medicines and Healthcare products Regulatory Agency (MHRA).

Indirect treatment comparison

An analysis that compares interventions that have not been compared directly within a head-to-head, randomised trial.

Information specialists (NICE guidance information services)

Specialists, based either at NICE or an external contractor, with expertise in information retrieval who provide information to support the decision-making groups.

Key areas for inclusion

The key aspects of care that the good practice guidance will cover in order to ensure it focuses on areas in which the NHS most needs advice. Key areas for inclusion relate to systems and processes for medicines use.

Lay member

A member of the Guidance Development Group with knowledge of the issues that are important to patients, carers and the public.


See 'Marketing authorisation'.

Marketing authorisation

An authorisation that covers all the main activities associated with the marketing of a medicinal product. Medicines that meet the standards of safety, quality and efficacy set by the Medicines and Healthcare products Regulatory Agency (MHRA) are granted a marketing authorisation (previously a product licence), which is normally necessary before they can be prescribed or sold.

Markov modelling

A decision-analytic technique that characterises the prognosis of a cohort of patients by assigning them to a fixed number of health states and then models transitions among health states.

Medicines and Healthcare products Regulatory Agency (MHRA)

The Executive Agency of the Department of Health responsible for protecting and promoting public health and patient safety by ensuring that medicines, healthcare products and medical equipment meet appropriate standards of safety, quality, performance and effectiveness, and are used safely.

MeSH (medical subject headings)

The US National Library of Medicine's controlled vocabulary thesaurus used for indexing articles from biomedical journals for databases such as MEDLINE.


The use of statistical techniques in a systematic review to integrate the results of included studies. (Definition from The Cochrane Collaboration website.)


A process of identifying relevant findings or other statements from the literature and sorting them into a pattern of evidence on the subject being studied.

Mixed treatment comparison

An analysis that compares 2 or more interventions using a combination of direct evidence (from trials that directly compare the interventions of interest) and indirect evidence (from trials that do not compare the interventions of interest directly).

Narrative summary

Summary of findings given as a written description.

Nominal-group technique

A technique used to reach agreement on a particular issue. It uses a variety of postal and direct contact techniques, with individual judgements being aggregated statistically to derive the group judgement.

Observational study

Retrospective or prospective study in which the investigator observes the natural course of events with or without control groups (for example, cohort studies and case–control studies).

Off-label prescribing

A situation where a drug is used to treat a condition or disease for which the drug regulatory authority has not granted a marketing authorisation for that particular use. Off‑label prescribing of a licensed medicine is particularly common in pregnant women and in children and young people, as these groups have often been excluded from clinical trials during drug development.

Personal social services

Care services for vulnerable people, including those with special needs because of old age or physical disability and children in need of care and protection. Examples are residential care homes for the elderly, home help and home care services, and social workers who provide help and support for a wide range of people. (Department of Health definition.)

PICO (population, intervention, comparison and outcome) framework

A structured approach for developing review questions that divides each question into 4 components: the population (the population under study); the interventions (what is being done); the comparators (other main treatment options); and the outcomes (measures of how effective the interventions have been).

Preliminary literature search/Scoping search

A search of the literature undertaken at the scoping stage to identify literature including guidance, legislation, national policies, key systematic reviews and economic evaluations relevant to the guidance topic.

Project plan

A document prepared by the NICE project team that describes the rationale for the project, key outputs and requirements for delivery of the project outputs. It is an internal document that provides the reference from which the progress of the work can be assessed.

Proprietary name

The brand name given by the manufacturer to a drug or device it produces.

Quality of life

See 'Health-related quality of life'.


The smallest number of group members that must be present to constitute a valid meeting. The quorum of a Guidance Development Group is 50% of appointed members. No business relating to the formulation of guidance recommendations may be conducted unless the quorum is reached.

Relative risk reduction

The proportional reduction in risk between experimental and control participants in a trial.


The brief that may be given by the Department of Health or NHS England at the start of good practice guidance development. This may define core areas of care that the guidance needs to address.

Research recommendation

Recommendations for future research covering questions relating to an uncertainty or evidence gap that has been identified during the guidance development process.

Resource implication

The likely impact in terms of finance, workforce or other NHS resources.

Review of the literature

An article that summarises the evidence contained in a number of different individual studies and draws conclusions about their findings. It may or may not be systematically researched and developed.

Review question

A structured question about the process, system and/or care that is formulated from a key issue in the scope to guide the systematic review. See also PICO framework.

Scope consultation table

A table of all the comments received by NICE during consultation on the guidance scope and responses. It is published on the NICE website with the final scope. (Good practice guidance will not always undertake scope consultation.)

Scoping workshop

A workshop led by the NICE project team with input from topic experts, NICE, and patient, carer and public representatives. The role of the group is to identify the key areas for inclusion in a piece of guidance and review the draft scope.

Search filter

A collection of search terms designed to retrieve selections of records (for example, records of research using a specific study design or on a specific topic).

Selection bias

1. Systematic differences between comparison groups in prognosis or responsiveness to treatment. Random allocation with adequate concealment of allocation protects against selection bias. Other means of selecting who receives the intervention are more prone to bias because decisions may be related to prognosis or responsiveness to treatment.

2. A systematic error in reviews due to how studies are selected for inclusion. Reporting bias is an example of this.

3. A systematic difference in characteristics between those who are selected for study and those who are not. This affects external validity but not internal validity.

(Definitions from The Cochrane Collaboration website.)

Sensitivity analysis

A means of representing uncertainty in the results of economic evaluations. Uncertainty may arise from missing data, imprecise estimates or methodological controversy. Sensitivity analysis also allows for exploring the applicability of results to other settings. The analysis is repeated using different assumptions to examine the effect on the results.

Deterministic sensitivity analysis: tests the impact of potential bias resulting from the selection of data sources for key model parameters.

One-way sensitivity analysis (univariate analysis): each parameter is varied individually in order to isolate the consequences of each parameter on the results of the study.

Probabilistic sensitivity analysis: probability distributions are assigned to the uncertain parameters and are incorporated into evaluation models based on decision analytical techniques (for example, Monte Carlo simulation).

Stakeholder scoping workshop

Workshop attended by registered stakeholders before consultation on the scope, to discuss the key clinical issues identified by the scoping group.

Study quality

The extent to which a study has conformed to recognised good practice in the design and execution of its research methods.

Synthesis of evidence

A generic term to describe methods used for summarising (comparing and contrasting) evidence in order to address a defined review question. This can include systematic review (with or without meta-analysis), and qualitative and narrative summaries.

Systematic review

Research that summarises the evidence on a clearly formulated review question according to a predefined protocol using systematic and explicit methods to identify, select and appraise relevant studies, and to extract, collate and report their findings. It may or may not use statistical meta-analysis.

Time horizon

The time span that reflects the period over which the main differences between interventions in health effects and use of healthcare resources are expected to be experienced, taking into account the limitations of supportive evidence.

Treatment allocation

The process by which study participants are allocated to a treatment group.

Treatment options

The choices of intervention available.