controlled study definition
Definition: An experiment or clinical trial in which two groups are used for comparison purpose. More: In a controlled exposure study, one group of participants is exposed to a substance (e.g. a pollutant) while those in the  control  group are not.The results are then compared to determine the health effects of the substance being studied.In a placebo controlled study (often called simply controlled study), people in the treatment group are given the drug or treatment being tested while the control group receives a placebo or a different treatment.Source: GreenFacts.n a placebo controlled study (often called simply controlled study), people in the treatment group are given the drug or treatment being tested while the control group receives a placebo or a different treatment. Source: GreenFacts.