In attempting to develop evidenced-based practice, the health professions face several challenges. The first is simply trying to ensure that providers are aware of good scientific evidence derived from research, and the second is to determine what constitutes good evidence. Here the gold standard is the randomized, double-blind, placebo-controlled trial. But a hierarchy of evidence has been established, ranging from the randomized controlled trial to the controlled trial to cohort studies to case series to case studies.
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