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.

  • Sample

    People in a study recruited from part of the study's target population. If they are recruited in an unbiased way, the results from the sample can be generalised to the target population as a whole.

  • Sampling

    The way people are selected for inclusion in a study.

  • Scenario

    An alternative set of assumptions to those the economic model is based on (the base case). Researchers use different scenarios to test how different assumptions (for example around costs, model structure or utilities) affect cost effectiveness.

  • Scientific value judgements

    NICE bases its decisions on the best available evidence. Sometimes the available evidence is not good quality or can be incomplete, so the committees involved have to make scientific value judgements and social value judgements. Scientific value judgements involve interpreting the quality, significance and relevance of all of the available scientific, technical and clinical data, including social scientific data. These judgements are used alongside the available evidence to inform recommendations.
  • Scope

    A document that describes what a piece of guidance will and will not cover. Depending on the type of guidance, organisations that are stakeholders, consultees or commentators can comment on the draft scope during a consultation period.
  • Scope consultation table

    A table of all the comments received by NICE during consultation on a scope, and responses to the comments. It is published on the NICE website with the final scope.
  • Secondary care

    Secondary care is healthcare provided in hospitals. It includes accident and emergency departments, outpatient departments, antenatal services, genitourinary medicine and sexual health clinics.
  • Secondary data

    Data collected routinely or collected for research when reused in other studies.

  • Selective outcome reporting

    Selecting outcomes to include in the publication of a trial based on results. The concern is that statistically non-significant results might be selectively withheld from publication.

  • Semistructured interview

    The interviewer asks a number of open-ended questions and follows up on areas of interest in response to the information given. It allows more flexibility than a structured interview, which involves asking preset questions.

  • Sensitivity (of a test)

    How well a test detects what it is testing for. It is the proportion of people with the disease or condition that are correctly identified by the study test. For example, a test with a sensitivity of 96% will, on average, correctly identify 96 people in every 100 who truly have the condition, but incorrectly identify as not having the condition 4 people in every 100 who truly have it. It is different from positive predictive value.

  • Sensitivity analysis

    A means of exploring uncertainty in the results of economic evaluations. There may be uncertainty because data are missing, estimates are imprecise or there is controversy about methodology. Sensitivity analysis can also be used to see how applicable results are to other settings. The analysis is repeated using different assumptions to examine the effect of these assumptions on the results.

  • Service delivery guidance

    Recommendations aimed primarily at health service commissioners. Service delivery guidance focuses on the broad configuration and provision of clinical services.
  • Shared learning database

    Case studies of good practice showing how NICE guidance has been implemented. The database allows organisations to learn from each other's experience of implementing NICE guidance.
  • Side effect

    An effect of a drug (or treatment or intervention) that is additional to the main intended effect. It could be good, bad or neutral, and that might depend on the circumstances. For example, a side effect of an antidepressant might be drowsiness. That could be a beneficial effect if a person with depression has problems sleeping, but not if they are trying to drive. See also Adverse effect.

  • SIGN

    Scottish Intercollegiate Guidelines Network (SIGN). SIGN was established in 1993 to sponsor and support the development of evidence-based clinical guidelines for the NHS in Scotland.
  • Single technology appraisal

    Technology appraisal guidance covering a single drug or treatment for a single indication.

  • Single-arm trial

    A clinical trial in which all participants receive the experimental intervention of interest. This is especially common in phase I and II trials.

  • Single-blind study

    See Blinding or masking

  • Social care

    Social care generally refers to all forms of personal care and other practical assistance for children, young people and adults who need extra support. This includes:

    • vulnerable children and young people (those who are at risk of, or who are already experiencing social and emotional problems)
    • children, young people and adults with learning or physical disabilities or mental health problems
    • people who misuse drugs or alcohol
    • older people.
  • Social marketing

    Using marketing principles and techniques as part of a health promotion campaign to persuade people to make a positive change in their behaviour to improve their health or prevent ill health.
  • Social value judgements

    The decisions in NICE guidance are based on the best available evidence. Sometimes the available evidence is not of good quality or can be incomplete, so the committees involved have to make scientific value judgements and social value judgements. Social value judgements take account of society’s expectations, preferences, culture and ethical principles when making recommendations. Our principles set out how committees should take into account factors such as the need to distribute health resources in the fairest way within society as a whole.

  • Socioeconomic status

    Description of a person's position in society using criteria such as their occupation, income or level of education.

  • Specificity (of a test)

    How well a test correctly identifies people who do not have what it is testing for. It is the proportion of people without the disease or condition that are correctly identified by the study test. For example, a test with a specificity of 96% will, on average, correctly identify 96 people in every 100 who truly do not have the condition, but incorrectly identify as having the condition 4 people in every 100 who truly do not have it. It is different from negative predictive value.


    A SPICE (setting, perspective, intervention, comparison and evaluation) framework is a structured approach for developing review questions. It divides each question into 5 components: the setting (the context of a study); the perspective (who it is for); the intervention(s) (what was done); the comparison (the other main interventions); and evaluation (what was found).

  • Stakeholder

    An organisation with an interest in a topic that NICE is developing guidance on. Organisations that register as stakeholders can comment on the draft scope and the draft guidance. Stakeholders may be:

    • local government and utilities in England
    • NHS organisations
    • national organisations or groups of and for people who use health and social care services, their families and carers, and the public
    • organisations representing people working in health and social care
    • local Healthwatch organisations
    • public sector providers and commissioners of care or services
    • private, voluntary sector and other independent providers of care or services
    • companies that manufacture drugs, devices, equipment or adaptations, and commercial industries relevant to public health
    • organisations that fund or carry out research
    • government departments and national statutory agencies.
  • Standard deviation

    A measure of the spread, scatter or variability of a set of measurements. Usually used with the mean (average) to describe numerical data.
  • Statistical analysis plan

    A technical document that describes in detail the planned statistical analyses for a study. It usually forms part of a study protocol.

  • Statistical association

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

  • Statistical power

    The ability of a study to demonstrate an association or causal relationship between 2 variables (if an association exists) means that the study is statistically significant. The statistical power of a study is primarily related to the number of people included. If too few people are included, any differences in the outcomes will not be statistically significant.
  • Statistical significance

    A statistically significant result is one that is assessed as being due to a true effect rather than random chance. See P value.

  • Structural uncertainty

    Uncertainty relating to the assumptions and judgements used to construct a model. These include:
    • design features of the model, for example, the assumed standard pathway of care
    • judgements about how relevant the evidence is
    • assumed appropriate distributions for parameters
    • alternative methods of estimation.
  • Structured data

    Data that follows a predefined data model such as patient characteristics, clinical diagnoses, and test results.

  • Structured interview

    A research technique in which the interviewer asks all the people in the study a list of pre-set questions.

  • Study checklist

    A set list of questions about the research methodology used to ensure a study is valid. A different checklist is used for each study type.
  • Study population

    People who are the subjects of a research study.
  • Study quality

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

    The way a study is designed. Case-control study, cohort study, non-randomised controlled trial, and randomised controlled trial are all examples of study types using different research methodologies.
  • Subgroup analysis

    A way to find out from a study if a treatment is more effective in one group of people (for example, who are a particular age or have particular symptoms) than another. It uses evidence from a defined subgroup within the whole analysis set.

  • Survey

    A study in which information is systematically collected from people (usually from a sample within a defined population).
  • Systematic

    Methodical, not random.
  • Systematic error

    Refers to the various errors or biases inherent in a study. See also Bias.

  • Systematic review

    A review 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, analyse, collate and report their findings. It may or may not use statistical techniques, such as meta-analysis.

  • Systemic

    Involving the whole body.
  • Systemic disease

    A disease that affects the person's whole body.