A control group in a scientific experiment is a group separated from the rest of the experiment where the independent variable being tested cannot influence the results. This isolates the independent variable's effects on the experiment and can help rule out alternate explanations of the experimental results.
Control groups can also be separated into two other types: positive or negative.
Positive control groups are groups where the conditions of the experiment are set to guarantee a positive result. A positive control group can show the experiment is functioning properly as planned.
Negative control groups are groups where the conditions of the experiment are set to cause a negative outcome.
Control groups are not necessary to all scientific experiments. Controls are extremely useful where the experimental conditions are complex and difficult to isolate.
Experiments & VariablesWhat Is an Experiment?
What Is a Variable in Science?
What Is an Independent Variable?
What Is a Dependent Variable?
What Is an Experimental Group?
Difference Between Control and Experimental Group