Group sample sizes in nonregulated health care intervention trials described as randomized controlled trials were overly similar

OBJECTIVES: We evaluated whether sample sizes in different arms of two-arm parallel group randomized controlled trials of nonregulated interventions were systematically closer in size than would plausibly occur by chance if simple randomization had been applied. STUDY DESIGN AND SETTING: We searched PubMed for trials of nonregulated health care interventions that did not report using restricted randomization from journals in behavioral sciences …