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Encyclopedia > Experimental control

Experimental controls are used in scientific experiments to prevent factors other than those being studied from affecting the outcome. Wikipedia does not have an article with this exact name. ... A scientific control augments integrity in experiments by isolating variables as dictated by the scientific method in order to make a conclusion about such variables. ... In the scientific method, an experiment (Latin: ex-+-periri, of (or from) trying), is a set of actions and observations, performed in the context of solving a particular problem or question, to support or falsify a hypothesis or research concerning phenomena. ...


Controls are needed to eliminate alternate explanations of experimental results. For example, suppose a researcher feeds an experimental artificial sweetener to thirty laboratory rats and observes that eight of them subsequently die of dehydration. The underlying cause of death could be the sweetener itself or something unrelated. Perhaps the rats were simply not supplied with enough water; or the water was contaminated and undrinkable; or the rats were under some psychological or physiological stress that caused them not to drink enough; or a disease dehydrated them; or their cage was kept too hot. Eliminating each of these possible explanations individually would be time-consuming and difficult. Instead, the researcher can use an experimental control, separating the rats into two groups: one group that receives the sweetener and one that doesn't. The two groups are kept in otherwise identical conditions, and both groups are observed in the same ways. Now, any difference in morbidity between the two groups can be ascribed to the sweetener itself--and no other factor--with much greater confidence. A sweetener is a food additive which adds the basic taste of sweetness to a food. ... This is an article about wild rats; for pet rats, see Fancy rat Species 50 species; see text *Several subfamilies of Muroids include animals called rats. ...


In other cases, an experimental control is used to prevent the effects of one variable from being drowned out by the known, greater effects of other variables. For example, suppose a program that gives out free books to children in subway stations wants to measure the effect of the program on standardized test scores. However, the researchers understand that many other factors probably have a much greater effect on standardized test scores than the free books: household income, for example, and the extent of parents' education. In scientific parlance, these are called confounding variables. In this case, the researchers can either use a control group or use statistical techniques to control for the other variables. In statistics, a spurious relationship (or, sometimes, spurious correlation) is a mathematical relationship in which two occurrences have no logical connection, yet it may be implied that they do, due to a certain third, unseen factor (referred to as a confounding factor or lurking variable). The spurious relationship gives an...


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  Results from FactBites:
 
Experimental control - Wikipedia, the free encyclopedia (238 words)
These control groups are useful to derive baselines measures or observations used for evaluating the results of an experiment.
Controls are used so that an experimenter can compare the group that has changed to the group that stayed the same.
To have a baseline measure we set up a control group which is fed with ordinary diet and have other groups which are fed a low carb diet (the experimental group).
Approaches to Evaluating Welfare Reform: Lessons from Five State Demonstrations: Chapter 4: Implementation of ... (6924 words)
Experimental cases in the sample of approved applicants were subject to control group policies for one month before the application of experimental group policies.
Anticipating their experimental or control status, recipients may decide to leave welfare before random assignment, and potential applicants may decide either not to apply for assistance or to apply with another individual identified as the case head.
When control group policies are changed, the resulting measures of the impacts of the welfare reform program will be biased, because the control group is subject to policies and situations qualitatively different from those that would have existed in the absence of welfare reform.
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