Table 1 Key concepts and key terms of the realist approach to evidence synthesis (adapted from Robert et al. [85], Dalkin et al. [86] and Pearson et al. [87])

Mechanism

Element of the reasoning of the actor facing an intervention (beliefs, values, desires and cognitive processes). A mechanism (1) is generally hidden, (2) is sensitive to context variations and (3) produces outcomes.

CMO configuration

Conceptual tool to link the elements of context, mechanisms and outcomes of an intervention

Programme theory

Set of hypotheses that explain how and why the intervention is expected to produce outcomes. It can be broken down in the form of one or more CMO configurations.

Middle-range theory

Level of theoretical abstraction that provides an explanation of semi-regularities in the CMO interactions of a set of interventions

Demi-regularity

A demi-regularity is a semi-predictable pattern or pathway of programme functioning

Juxtaposition, reconciling, adjudication and consolidation of sources of evidence and situating sources of evidence

-Juxtapose, to place two or more things (evidence fragments) together, especially in order to suggest a link between them or emphasise the contrast between them

-Reconcile, to make two or more apparently conflicting things (evidence fragments) consistent or compatible

-Adjudicate, to make a judgement about methodological quality or applicability in this instance and account for this judgement based on findings from the use of the critical appraisal tool, or an explicit argument about why a piece of evidence was not applicable

-Consolidate, to bring together. In a realist synthesis, ‘to bring together into a more coherent whole’

-Situate, to place something (a piece or pieces of evidence) in a context or set of circumstances and show the connections (between it/them and other evidence fragments)