Table 4

Traditional biomedical versus complex systems paradigms (reproduced and adapted under CC-BY-4.0 licence from Greenhalgh and Papoutsi)41

Traditional biomedical paradigmComplex systems paradigm
Scientific truth viewed asSingular (ie, there is one set of facts which will be found by using the correct scientific methods)Multiple (ie, there are many legitimate scientific perspectives on a problem, so multiple methods may be needed)
Goal of researchEstablishing the truth, which is seen as universal and generalisableExploring tensions; generating insights; revealing multiple perspectives
Assumed model of causalityLinear, cause-and-effect; a fixed input has a fixed effect sizeEmergent: many interacting influences, but none has a fixed ‘effect size’
Typical format of research question‘What is the effect size of the intervention on the predefined outcome, and is it statistically significant?’‘What combination of influences has generated this phenomenon? What does the intervention of interest contribute? What happens to the system and its actors if we intervene in a particular way? What are the unintended consequences elsewhere in the system?’
Good research defined in terms ofMethodological rigour, standardisation, precisionStrong theory, flexible methods, pragmatic adaptation to changing circumstances
Most valued study designsRandomised controlled trials, meta-analysesNo single design is ‘most valued’. A combination of designs—for example, multilevel intervention studies, naturalistic case studies, modelling studies—is preferred
Purpose of theorisingDisjunctive (simplification and abstraction)Conjunctive (drawing together different parts of a complex problem)
Approach to data collectionContinue collecting data until the dataset is complete and agreedData will never be complete; decisions must sometimes be made on the basis of incomplete or contested data
Analytic focusDualisms: comparing A with B; finding the influence of X on YDualities: inter-relationships and tensions between A, B, C and other emergent phenomena