The experimental group in a clinical study is the group which receives the actual drug or treatment being studied. The control group group and experimental group must be identical in all relevant ways except for the introduction of a suspected causal agent into the experimental group.
Controls, double blind procedure, and randomized testing are used to reduce error, self-deception and bias.
Double blind procedure is a method of enhancing internal validity in an experiment. In double blind procedure, neither the researcher nor the subjects are made aware of which group is the experimental group and which is the control group.
Control groups are used in controlled experiments to curb bias. Both control group and experimental groups are treated exactly the same in every way possible except for variable difference.
Control groups are not manipulated. They are used to compare the experimental group against. The control group is used so that you have something to compare the experimental group to.
In a double-blind study in clinical trials: two identical groups, control group and experimental group, of patients are compared, one of which receives the drug and one of which receives a placebo. The patients and the doctor know which group receives the real drug, which serves to curb bias.