Invited commentary on "Discrimination of real and sham acupuncture needles using the park sham device: a preliminary study".

Peter T. Dorsher, MS, MD, provides an interesting commentary on the findings of a study by Tan and colleagues that was highlighted in the December issue of the Archives as displaying potential deficiencies in a number of sham acupuncture devices. Dr. Dorsher's comments, while focused on acupuncture, are interesting in their own right. However, a little thought shows that his insights into the nature of an adequate placebo provide an improved understanding of the issues involved in the design and validation of control interventions in general.