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Randomized Control Trial (RCT)

A study in which the participants are divided by chance into separate groups that compare different treatments or other interventions. Using chance to divide people into groups means that the groups will be similar and that the effects of the treatments they receive can be compared more fairly. At the time of the trial, it is not known which treatment is best.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

The random allocation section of the CONSORT flow chart for clinical trials Click to enlarge

Random allocation for patients in a clinical trial with two groups CONSORT

About Randomized Trials

In the late 1940s, groups of researchers in Europe and the USA led one of the most important developments of modern medical science: they refined the methods for testing treatments in randomized controlled studies or "trials.""Randomized" means that volunteers are divided into groups by chance, like in a lottery. One of the groups then uses the treatment being tested. The experiences of the other group of people provide control or comparison data.

This makes it possible to see what effects the treatment actually has, and to make sure that the groups are not different from the start — for example, because one group has healthier people in it. This simple approach provides a way to find out if a treatment is effective, useless or even harmful... Read more about Randomized Control Trial

Articles on this research topic

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Empirical Evidence of Associations Between Trial Quality and Effect Size [Internet]

To examine the empirical evidence for associations between a set of proposed quality criteria and estimates of effect sizes in randomized controlled trials across a variety of clinical fields and to explore variables potentially influencing the association.

Finding Evidence on Ongoing Studies [Internet]

Comparative effectiveness reviews synthesize evidence to inform questions about healthcare topics, but the evidence is not always sufficient to completely answer those questions. Therefore systematic reviews and specifically Evidence-based Practice Center (EPC) reports may identify research gaps and make recommendations for future research to address these unanswered questions. One useful adjunct to these recommendations is an analysis of the research that is currently in the pipeline. This additional information can be used to prioritize the research gaps in the report. Identified research gaps on topics for which several large studies are underway can be described as a lower priority future research need. Identified research gaps on topics with few studies underway may rise as priorities for future research. Prioritizing the research gaps this way can also guide funding agencies in decisions about which topics may need additional research funding. The information provided about ongoing studies can provide indications about when to update reviews.

Case Study Comparing Bayesian and Frequentist Approaches for Multiple Treatment Comparisons [Internet]

Bayesian statistical methods are increasingly popular as a tool for meta-analysis of clinical trial data involving both direct and indirect treatment comparisons. However, appropriate selection of prior distributions for unknown model parameters and checking of consistency assumptions required for feasible modeling remain particularly challenging. We compared Bayesian and traditional frequentist statistical methods for multiple treatment comparisons in the context of pharmacological treatments for female urinary incontinence (UI).

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Terms to know

CONSORT Statement
CONSORT (Consolidated Standards Of Reporting Trials) minimum set of recommendations for reporting randomized...
Clinical Trial
A type of research study that tests how well new medical approaches work in people. These studies test new m...
Random Allocation (Randomization)
A process involving chance used in therapeutic trials or other research endeavor for allocating experimental...

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