In science, controls are intended to reduce or eliminate false-positive results that arise from confirmation bias or the placebo effect. According to psychology expert Kendra Cherry for About.com, controls are especially useful in medical research as a way of insulating the people assessing the effectiveness of a treatment from those who analyze the results by randomizing the test subjects into groups and giving one group an ineffective treatment.Continue Reading
Controls, such as administering a placebo to one group of patients, are crucial to collecting reliable data. According to Wikipedia, a properly designed double-blind study ensures the placebo effect is eliminated, and observer bias is reduced by preventing patients and observers from knowing which medication is being administered. A properly constructed control factor helps to isolate only the variable being studied.
In principle, the presence of the agent or factor being studied is the only difference between test populations and the control group, which ensures that any significant differences between the two groups must be a result only of the factor being tested, notes Wikipedia. Controls are also effective at reducing the risk of contamination, as when blood samples are collected from a crime scene. A positive result in the test field and a negative result in the control area increases confidence in the test's accuracy, as a contaminated sample is likely to test positive in both areas.Learn more about Law