Table 1. Limitations of the Randomized Controlled Trial

• Inclusion and exclusion criteria may significantly restrict participants’ enrollment. They are thought to create more homogenous samples, but after a point the cohorts do not reflect the clinical entity.
• Short course of study does not allow long-term conclusions to be made.
• Real-life confounding variables that are involved in every clinical encounter in which a therapy is prescribed (e.g., belief, expectancy, relationship, rapport) are removed.
• Patients are not given a choice of therapy, thus removing empowerment and expectancy that they are going to receive the best therapy.
• Only group means are considered relevant, and individual variations are ignored (Witter, Simon, & Dionne, 2003).

From “Limitations of randomized clinical trials in chronic diseases: Explanations and recommendations,” by T. Pincus, 2002, Advances in Mind-Body Medicine, 18(2), 14–21.