Participant expectancies in double-blind randomized placebo-controlled trials: potential limitations to trial validity

Participants' expectancies can undermine the validity of double-blind placebo-controlled RCTs. Researchers conducting these trials should assess participants' beliefs about their treatment allocation and actively investigate if and how these beliefs may have influenced the trial's outcome. Clinical Trials 2010; 7: 246-255. http://ctj.sagepub.com.