Glossary of Terms

Term Definition
Accuracy In the context of diagnostic testing, accuracy refers to the ability of a test to discriminate between the target condition and the corresponding true condition. 1
Burden of illness Generally describes the cumulative consequences of a defined illness or disease. These consequences may include health, costs, and social implications. 2
Diagnostic test A diagnostic test or procedure is an examination used to gather clinical information on an individual in order to make a diagnosis on a condition, disease or illness (e.g. x-rays, CT scan etc.). 3
Fixed review question A fixed question can have elements of the PICO (Population, Intervention, Comparison, and Outcome) approach that is used in a quantitative knowledge synthesis of interventions (e.g., systematic review and meta-analysis).4 These elements serve to “anchor” a synthesis. For example, these elements could be used as keywords in a literature search to identify relevant studies and aggregate the findings. 4
Emergent review question For the conduct of the qualitative knowledge synthesis, an emergent question generally does not have a set of pre-defined parameters. It can be modified to reflect the understanding that the review team acquire during the review conduct. At the start of the review or during the review, one can restate an emergent review question as a review objective, which serves as a “compass” that offers a general direction for the review conduct. 4
Epidemiology Epidemiology is the study of how often diseases occur in different groups of people and why. A key feature of epidemiology is the measurement of disease outcomes in relation to a population at risk (i.e., group of people, healthy or sick, who would be counted as cases if they had the disease being studied). 5
Epistemology The assumptions on the nature of knowledge that underpin the synthesis method and the extent to which these permit the review team to achieve their purpose.4
Intervention An intervention in the context of health is an act performed for, with or on behalf of a person or population whose purpose is to assess, improve, maintain, promote or modify health, functioning or health conditions.6
Method Techniques researchers use for practicing the craft of research.8 Within the context of research synthesis, methods might be instruments for data collection such as data collection forms, tools used for performing quality assessment or extracting themes from study data, or the term might refer to aspects of the research process like sampling, among others.9
Methodology Simply put, methodology refers to the study of the methods (i.e., overall strategies) used by researchers or reviewers to address their chosen research question.10 A methodology may draw upon several methods and is concerned with uncovering the practices and assumptions of those who use different types of methods. 8, 9
Sampling method Sampling method – Sampling method in knowledge synthesis refers to the process of selecting a subset of studies for inclusion into a review.10
Qualitative evidence synthesis An umbrella term for the methodologies associated with the systematic review of qualitative research evidence, conducted either as a stand-alone review or as a part of a large review, such as a review of an intervention and the experience of patients enduring the illness.11
Quantitative study A quantitative research study is an investigation of phenomena that lend themselves to test well-specified hypotheses through precise measurement and quantification of predetermined variables that yield numbers suitable for statistical analysis.12
Qualitative study A qualitative research study focuses on social and interpreted phenomena (rather than quantifiable) and aims to discover, interpret, and describe rather than to test and evaluate. The study aims to make inductive, descriptive inferences to theory concerning social experiences or settings, whereas quantitative research makes causal or correlational inferences to populations.12


  1. Šimundić AM. Measures of Diagnostic Accuracy: Basic Definitions. EJIFCC. 2009;19(4):203-11.
  2. Hessel F. Burden of DiseaseBurdenof disease(s). In: Kirch W, editor. Encyclopedia of Public Health. Dordrecht: Springer Netherlands; 2008. p. 94-6.
  3. Diagnostic Test or Diagnostic Study Definition: VERITAS health; [cited 2020 October 27]. Available from:
  4. Booth A, Noyes J, Flemming K, Gerhardus A, Wahlster P, van der Wilt GJ, et al. Structured methodology review identified seven (RETREAT) criteria for selecting qualitative evidence synthesis approaches. J Clin Epidemiol. 2018;99:41-52.
  5. BMJ T. Chapter 1. What is epidemiology? 2021 [Available from:
  6. Organization WH. International Classification of Health Interventions (ICHI) [cited 2020 October 27]. Available from:
  7. Grimshaw J. A Guide to Knowledge Synthesis [cited 2020 October 27]. Available from:
  8. Bryman A. Of methods and methodology. Qual Res Organ Manag. 2008;3(2):159-68.
  9. Booth A, Noyes J, Flemming K, Gerhardus A, Wahlster P, Van Der Wilt G, et al. Guidance on choosing qualitative evidence synthesis methods for use in health technology assessments of complex interventions. Bremen (DE): Integrate-HTA. 2016.
  10. Benoot C, Hannes K, Bilsen J. The use of purposeful sampling in a qualitative evidence synthesis: A worked example on sexual adjustment to a cancer trajectory. BMC Medical Research Methodology. 2016;16(1):21.
  11. Carroll C. Qualitative evidence synthesis to improve implementation of clinical guidelines. BMJ. 2017;356:j80.
  12. Network J. JAMA evidence Glossary 2020 [cited 2020 October 27]. Available from: