Why do we need randomised controlled trials to assess behavioural interventions?

Merits of randomised controlled trials in behavioural and psychosocial research do not differ fundamentally from those in clinical medicine. Interventions that target behaviour are often complex and demanding, as are the requirements of good randomised controlled trials to assess their efficacy. Standardising the content and delivery of an intervention in a trial may be more challenging than justifying randomisation during informed consent. When blinding of participants and researchers to treatment allocation is impossible, it is important to minimise bias through blinded assessment of the outcome. The contribution that participant choice makes to the efficacy of an intervention is hard to measure