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A quasi-experiment is an empirical interventional study used to estimate the causal impact of an intervention on target population without random assignment.Quasi-experimental research shares similarities with the traditional experimental design or randomized controlled trial, but it specifically lacks the element of random assignment to treatment or control.
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 ...
This is in contrast to traditional single-arm (i.e. non-randomized) clinical trials or randomized clinical trials (RCTs) that are static in their protocol and do not modify any parameters until the trial is completed. The adaptation process takes place at certain points in the trial, prescribed in the trial protocol.
An experimental design or randomized clinical trial requires careful consideration of several factors before actually doing the experiment. [32] An experimental design is the laying out of a detailed experimental plan in advance of doing the experiment.
Randomized clinical trials analyzed by the intention-to-treat (ITT) approach provide unbiased comparisons among the treatment groups. Intention to treat analyses are done to avoid the effects of crossover and dropout, which may break the random assignment to the treatment groups in a study. ITT analysis provides information about the potential ...
Open-label trials may be appropriate for comparing two similar treatments to determine which is most effective, such as a comparison of different prescription anticoagulants, [4] or possible relief from symptoms of some disorders when a placebo is given. [5] An open-label trial may still be randomized.
Randomized, controlled, crossover experiments are especially important in health care. In a randomized clinical trial, the subjects are randomly assigned treatments. When such a trial is a repeated measures design, the subjects are randomly assigned to a sequence of treatments.
A 2008 study of 146 meta-analyses concluded that the results of randomized controlled trials with inadequate or unclear allocation concealment tended to be biased toward beneficial effects only if the trials' outcomes were subjective as opposed to objective. [4] Allocation concealment is different from blinding.