Randomized controlled trials: methodological concepts and critique.

Randomized controlled trials, also known as true experiments or intervention studies, are considered to be the gold standard research design for demonstrating a cause-and-effect relationship between an intervention and an outcome. This article will describe key methodological concepts that make the randomized controlled trial this gold standard. Practicing from an evidence-based perspective requires practitioners to be able to critique the strengths and weaknesses of a research study in order to make decisions about adoption of the intervention into one's practice area. Key components to the critique of a randomized controlled trial are defined and the process is illustrated by a critique of Gallo and colleagues article, A Study of Naloxone Effect on Urinary Retention in the Patient Receiving Morphine PCA, published in this issue.