Table 1

Assumptions made in conducting randomized controlled trials

Equipoise
Patient and provider do not have a preference for a treatment
Lack of knowledge
It is truly unknown which of two alternatives is "better" and there is insufficient evidence about treatment effects from other sources
Preference for specificity
Only specific effects attributable to the intervention are therapeutically valid
Context independence
There is a "true" magnitude of efficacy, or a stable effect size independent of context
Ecological and external validity knowable
The knowledge about a therapeutic effect extracted from an RCT is readily transferable into clinical practice, if exclusion and inclusion criteria of the trial match the characteristics of a given patient

Walach et al. BMC Medical Research Methodology 2006 6:29   doi:10.1186/1471-2288-6-29