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.
- Implementation advice
Advice on how to put into practice a specific piece of guidance. This advice is for NHS staff whose job includes ensuring this happens. The advice includes an action plan that staff can use.
- Implementation tools
- In depth interview
A qualitative research technique. It is a face to face conversation between a researcher and a respondent with the purpose of exploring issues or topics in detail. Does not use pre-set questions, but is shaped by a defined set of topics or issues.
The number of new cases of a disease divided by the total population at risk during a certain period. It is often expressed as numbers per million. See also prevalence.
- Inclusion criteria
See selection criteria.
- Incremental cost
The extra cost linked to using one test or treatment rather than another. Or the additional cost of doing a test or providing a treatment more frequently.
- Indepth interview
A qualitative research technique that involves a detailed, face-to-face conversation between a researcher and a respondent on a particular issue or topic. It does not use pre-set questions.
A statistic or marker that has been chosen to monitor health or service activity. For example, an indicator might be the number of women attending for breast cancer screening or the number of deaths from coronary heart disease in a defined population.
- Information bias
This can affect all types of research study. It can be caused by questionnaires that have difficult or biased questions, observer or interviewer errors (for example, lack of blinding), response errors (for example, if patients are aware of the treatment they receive) or measurement error (for example, a faulty machine).
- Intention-to-treat analysis
An assessment of the people taking part in a clinical trial, based on the group they were initially (and randomly) allocated to. This is regardless of whether or not they dropped out, fully complied with the treatment or switched to an alternative treatment. Intention-to-treat analyses are often used to assess clinical effectiveness because they mirror actual practice: that is, not everyone complies with treatment and the treatment people receive may be changed according to how they respond to it.
- Internal validity
A measure of how well a research study has been designed. That is, the extent to which the cause-and-effect relationships in a study are true for the people and conditions of the study. See also validity.
In medical terms this could be a drug treatment, surgical procedure, diagnostic or psychological therapy. Examples of public health interventions could include action to help someone to be physically active or to eat a more healthy diet.
- Interventional procedure
A procedure used for diagnosis or treatment. It involves making a cut or hole in the patient's body, entering into a body cavity or using electromagnetic radiation (including X-rays or lasers). NICE produces guidance on specific interventional procedures, see NICE interventional procedures guidance.
- Interventional Procedures Advisory Committee (IPAC)
The independent committee that advises NICE on whether an interventional procedure is safe enough and works well enough to be used in the NHS. The committee usually discusses each procedure twice. The first time, it produces the draft guidance (called the interventional procedures consultation document), based on the research and discussion with experts. The second time, it revises the guidance after a consultation to produce a document called the final interventional procedures document. The committee's members include clinicians who carry out interventional procedures, people who are familiar with the issues affecting patients and carers, and experts in assessing different treatments and the regulation of healthcare.
- Interventional procedures consultation document (IPCD)
The Interventional Procedures Advisory Committee's draft guidance on an interventional procedure, which covers how safe it is and how well it works. The equipment manufacturer and organisations registered as consultees can comment on the draft guidance during a consultation that lasts 4 weeks. The draft guidance is also posted on our website.
- Interventional procedures guidance (IPG)
NICE guidance about whether an interventional procedure is safe enough and works well enough to be used in the NHS. The term 'interventional procedure' means any surgery, test or treatment that involves entering the body through skin, muscle, a vein or artery, or a body cavity.
This page was last updated: 15 April 2011