Randomized controlled trial (RCT)
Research Methods
Definition. A randomized controlled trial assigns participants at random to intervention and control groups so that differences in outcomes can be attributed to the intervention.
Explanation
Randomisation balances known and unknown confounders on average. Cluster randomised trials allocate groups, such as clinics, as in a programme to increase physical activity in type 2 diabetes (Alghafri, 2018). Placebo-controlled RCTs can also show the absence of effect, for example of vitamin D in autism (Kerley et al., 2017).
Related concepts
Cohort study Confounding Risk of bias Causal inference Evidence-based medicine
Read on The Health Topics
- WhatsApp in Diabetes Care: What 90 Studies Actually Tell Us
- Nutrition and Autism Spectrum Disorder: Current Evidence
References
Alghafri, T. S., et al. (2018). MOVEdiabetes: A cluster randomized controlled trial to increase physical activity in adults with type 2 diabetes in Oman. BMJ Open Diabetes Research & Care, 6, e000489. https://doi.org/10.1136/bmjdiab-2017-000489
Kerley, C. P., Power, C., Gallagher, L., & Coghlan, D. (2017). Lack of effect of vitamin D3 supplementation in autism: A 20-week, placebo-controlled RCT. Archives of Disease in Childhood, 102(11), 1030–1036. https://doi.org/10.1136/archdischild-2017-312783
Cite this entry: Kurutkan, M. N. (2026). Randomized controlled trial (RCT). In The Health Topics glossary. https://healthtopic.org/glossary/randomized-controlled-trial/