Assertion: chest pain's number | /r/CapableOf | lack credible controls
Facets:
value: for placebo
type: TRANSITIVE-OBJECT
value: for expectation
type: PURPOSE
Source sentences:
text: A 2007 review of 13 studies found evidence for the efficacy of hypnosis in the reduction of chronic pain under some conditions, though the number of patients enrolled in the studies was low, raising issues related to the statistical power to detect group differences, and most lacked credible controls for placebo or expectation.