title: The evidence that evidence-based medicine omits.
abstract: According to current hierarchies of evidence for EBM, evidence of correlation (e.g., from RCTs) is always more important than evidence of mechanisms when evaluating and establishing causal claims. We argue that evidence of mechanisms needs to be treated alongside evidence of correlation. This is for three reasons. First, correlation is always a fallible indicator of causation, subject in particular to the problem of confounding; evidence of mechanisms can in some cases be more important than evidence of correlation when assessing a causal claim. Second, evidence of mechanisms is often required in order to obtain evidence of correlation (for example, in order to set up and evaluate RCTs). Third, evidence of mechanisms is often required in order to generalise and apply causal claims. While the EBM movement has been enormously successful in making explicit and critically examining one aspect of our evidential practice, i.e., evidence of correlation, we wish to extend this line of work to make explicit and critically examine a second aspect of our evidential practices: evidence of mechanisms.
authors.affiliation: Department of Science and Technology Studies, University College London, UK.
authors.forename: Brendan
authors.initials: B
authors.lastname: Clarke
authors.forename: Donald
authors.initials: D
authors.lastname: Gillies
authors.forename: Phyllis
authors.initials: P
authors.lastname: Illari
authors.forename: Federica
authors.initials: F
authors.lastname: Russo
authors.forename: Jon
authors.initials: J
authors.lastname: Williamson
mesh_terms: D015984:Causality; D015986:Confounding Factors, Epidemiologic; D019317:Evidence-Based Medicine / Q000379:methods / Q000592:standards; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000592:standards; D015203:Reproducibility of Results
keywords: Evidence; Evidence hierarchy; Evidence-based medicine; Mechanism; Methods; Philosophy; RCT