Randomized Comparative Experiment

A Randomized Comparative Experiment is a randomized assignment comparative experiment that follow a randomized controlled experiment design (with randomized controlled experiment treatment group(s) and a randomized controlled experiment control group(s)).

• AKA: Randomized Control Trial (RCT), Randomized Controlled Experiment.
• Context:
  • It can be managed by a Randomized Comparative Experiment System.
  • It can be designed by a Randomized Comparative Experiment Design Task.
  • It can be analyzed by a Randomized Comparative Experiment Evaluation Task.
  • It can (typically) be more costly to perform than a Post-hoc Analysis on Observational Data.
  • It can (typically) assume that any differences between the two groups are due either to the Treatment or to Random Variation. *** The Treatment can be considered Effective if the difference is Statistically Significant and not by Chance ..
  • It can range from being a Two-Group Randomized Experiment to being a Multi-Group Randomized Experiment.
  • It can range from being a Subject-level Randomized Experiment(RCT) to being a Cluster-Randomized Experiment(GRT).
  • It can range from being a Non-Blind Randomized Controlled Experiment to being a Double-Blind Randomized Controlled Experiment.
  • It can range from being a Placebo-Controlled Randomized Experiment to being an A-B Randomized Experiment.
  • It can range from being a Single-Factor per Treatment Controlled Experiment to being a Multi-Factor per Treatment Controlled Experiment.
  • It can range from being a Parallel Randomized Experiment to being a Repeated Measures Randomized Experiment.
  • It can range from being a Purely Randomized Controlled Experiment to being a Block Randomized Controlled Experiment.
  • It can be categorized by a Randomized Trial Assessment, such as the CONSORT 2010 Checklist.
• Example(s):
  • a Randomized Clinical Trial.
  • a Randomized Experiment with Baseline and Post-Treatment Measures.
  • a Champion-Challenger Experiment.
  • …
• Counter-Example(s):
  • a Randomized Experiment Without Comparator.
  • a Non-Randomized Controlled Experiment, such as Louis Pasteur's spontaneous generation disproof experiment.
  • a Stable Repeatable Observable Stochastic Process (aka random experiment)
  • a Natural Experiment.
  • a Quasi-Randomized Controlled Experiment.
• See: Matched Control Experiment, Evidence-Based Practice, Decentralized Clinical Trial.

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References

2021a

• (Wikipedia, 2021) ⇒ https://en.wikipedia.org/wiki/Randomized_controlled_trial Retrieved:2021-9-26.
  • A randomized controlled trial (or randomized control trial; 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 or other medical treatments.

    Participants who enroll in RCTs differ from one another in known and unknown ways that can influence study outcomes, and yet cannot be directly controlled. By randomly allocating participants among compared treatments, an RCT enables statistical control over these influences. Provided it is designed well, conducted properly, and enrolls enough participants, an RCT may achieve sufficient control over these confounding factors to deliver a useful comparison of the treatments studied.

2021b

• (UNICEF, 2021) ⇒ https://www.unicef-irc.org/KM/IE/impact_7.php Retrieved:2021-9-26.
  • QUOTE: A randomized controlled trial (RCT) is an experimental form of impact evaluation in which the population receiving the programme or policy intervention is chosen at random from the eligible population, and a control group is also chosen at random from the same eligible population. It tests the extent to which specific, planned impacts are being achieved. The distinguishing feature of an RCT is the random assignment of units (e.g. people, schools, villages, etc.) to the intervention or control groups. One of its strengths is that it provides a very powerful response to questions of causality, helping evaluators and programme implementers to know that what is being achieved is as a result of the intervention and not anything else.

2021c

• (GW, 2021) ⇒ https://himmelfarb.gwu.edu/tutorials/studydesign101/rcts.cfm Retrieved:2021-9-26.
  • QUOTE: A study design that randomly assigns participants into an experimental group or a control group. As the study is conducted, the only expected difference between the control and experimental groups in a randomized controlled trial (RCT) is the outcome variable being studied.

2018

• (Hariton & Locascio, 2018) ⇒ Eduardo Hariton, and Joseph J. Locascio (2018). "Randomised controlled trials—the gold standard for effectiveness research". In: BJOG: an international journal of obstetrics and gynaecology, 125(13), 1716.
  • QUOTE: Randomized controlled trials (RCT) are prospective studies that measure the effectiveness of a new intervention or treatment. Although no study is likely on its own to prove causality, randomization reduces bias and provides a rigorous tool to examine cause-effect relationships between an intervention and outcome. This is because the act of randomization balances participant characteristics (both observed and unobserved) between the groups allowing attribution of any differences in outcome to the study intervention. This is not possible with any other study design.

2016

• Amy Gallo. (2016). “A Refresher on Randomized Controlled Experiments.” In: HBR, MARCH 30, 2016
  • QUOTE: ere are the basic steps:
    1. Decide what your dependent variable of interest is (remember there might be more than one). In our oil well example, it’s the speed or efficiency with which you drill the well.
    2. Determine what the population of interest is. Are you interested in understanding whether the new bit works in all of your wells or just specific types of ones?
    3. Ask yourself, What is it we’re trying to do with this experiment? What is the null hypothesis­ — the straw man you’re trying to disprove? What is the alternative hypothesis? Your null hypothesis in this case might be, “There is no difference between the two bits.” Your alternative hypothesis might be, “The new drill bit is faster.”
    4. Think through all of the factors that could spoil your experiment — for example, if the drill bits are attached to different types of machines or are used in particular types of wells.
    5. Write up a research protocol, the process by which the experiment gets carried out. How are you going to build in the controls? How big of a sample size do you need? How are you going to select the wells? How are you going to set up randomization?
    6. Once you have a protocol, Redman suggests you do a small-scale experiment to test out whether the process you’ve laid out will work. “The reason to do a pilot study is that you’re most likely going to fall on your a**, and it hurts less when it’s called a pilot study,” he jokes. With an experiment like the drill bit one, you may skip the pilot because of the cost and time involved in drilling a well.
    7. Revise the protocol based on what you learned in your pilot study.
    8. Conduct the experiment, following the protocol as closely as you can.
    9. Analyze the results, looking for both planned results and keeping your eyes open for unexpected ones.

2011

• (Kabisch et al., 2011) ⇒ Maria Kabisch, Christian Ruckes, Monika Seibert-Grafe, and Maria Blettner (2011). "Randomized Controlled Trials Part 17 of a Series on Evaluation of Scientific Publications". In: Deutsches Arzteblatt International, 108(39), 663.
  • QUOTE: [[Randomized controlled clinical trials (RCTs)]] are the gold standard for ascertaining the efficacy and safety of a treatment. RCTs can demonstrate the superiority of a new treatment over an existing standard treatment or a placebo. In clinical research RCTs are used to answer patient-related questions, and in the development of new drugs they form the basis for regulatory authorities’ decisions on approval. Alongside meta-analyses, high-quality RCTs with a low risk of systematic error (bias) provide the highest level of evidence.

2003a

• (Dimitrov & Rumrill, 2003) ⇒ Dimiter M. Dimitrov, and Phillip D. Jr Rumrill. (2003). “Pretest-posttest Designs and Measurement of Change.” In: WORK: A Journal of Prevention, Assessment and Rehabilitation, 20(2).
  • QUOTE: … RD = randomized design (random selection and assignment of participants to groups and, then, random assignment of groups to treatments). With the RDs discussed in this section, one can compare experimental and control groups on (a) posttest scores, while controlling for pretest differences or (b) mean gain scores, that is, the difference between the posttest mean and the pretest mean. Appropriate statistical methods for such comparisons and related measurement issues are discussed later in this article.

2003b

• (Kendall, 2003) ⇒ J.M. Kendall (2003). "Designing a research project: randomised controlled trials and their principles". In: Emergency medicine journal: EMJ, 20(2), 164.
  • QUOTE: The randomised control trial (RCT) is a trial in which subjects are randomly assigned to one of two groups: one (the experimental group) receiving the intervention that is being tested, and the other (the comparison group or control) receiving an alternative (conventional) treatment (fig 1). The two groups are then followed up to see if there are any differences between them in outcome. The results and subsequent analysis of the trial are used to assess the effectiveness of the intervention, which is the extent to which a treatment, procedure, or service does patients more good than harm. RCTs are the most stringent way of determining whether a cause-effect relation exists between the intervention and the outcome.

Figure 1: The randomised control trial.

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