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A nested case–control (NCC) study is a variation of a case–control study in which cases and controls are drawn from the population in a fully enumerated cohort. [1] Usually, the exposure of interest is only measured among the cases and the selected controls. Thus the nested case–control study is more efficient than the full cohort design.
A randomized controlled trial (or randomized control trial; [2] RCT) is a form of scientific experiment used to control factors not under direct experimental control. Examples of RCTs are clinical trials that compare the effects of drugs, surgical techniques, medical devices, diagnostic procedures, diets or other medical treatments. [3] [4]
In medicine an intention-to-treat (ITT) analysis of the results of a randomized controlled trial is based on the initial treatment assignment and not on the treatment eventually received. ITT analysis is intended to avoid various misleading artifacts that can arise in intervention research such as non-random attrition of participants from the ...
In medicine, a stepped-wedge trial (or SWT) is a type of randomised controlled trial (RCT). An RCT is a scientific experiment that is designed to reduce bias when testing a new medical treatment, a social intervention, or another testable hypothesis.
Web sites can run randomized controlled experiments [2] to create a feedback loop. [3] Key differences between offline experimentation and online experiments include: [3] [4] Logging: user interactions can be logged reliably. Number of users: large sites, such as Amazon, Bing/Microsoft, and Google run experiments, each with over a million users.
In medicine, a crossover study or crossover trial is a longitudinal study in which subjects receive a sequence of different treatments (or exposures). While crossover studies can be observational studies , many important crossover studies are controlled experiments , which are discussed in this article.
Such a test or clinical trial is called a placebo-controlled study, and its control is of the negative type. A study whose control is a previously tested treatment, rather than no treatment, is called a positive-control study, because its control is of the positive type. Government regulatory agencies approve new drugs only after tests ...
Randomized controlled trial [5]. Blind trial [6]; Non-blind trial [7]; Adaptive clinical trial [8]. Platform Trials; Nonrandomized trial (quasi-experiment) [9]. Interrupted time series design [10] (measures on a sample or a series of samples from the same population are obtained several times before and after a manipulated event or a naturally occurring event) - considered a type of quasi ...