Control Variable
A control variable is a term used in scientific experiments to refer to a quantity that is held constant during the experiment. The purpose of holding a control variable constant is to isolate the effect of the independent variable on the dependent variable.
In order for an experiment to be valid, it is important that all extraneous variables be controlled. Extraneous variables are any variables other than the independent variable that could potentially affect the outcome of the experiment. By keeping all extraneous variables constant, we can be confident that any differences in the dependent variable are due solely to the independent variable.
There are two types of control variables: experimental and subject. Experimental control variables are those that are controlled by the experimenter, such as the type of material used or the conditions under which an experiment is conducted. Subject control variables are those that cannot be controlled by the experimenter, such as gender or ethnicity. In order for an experiment to be valid, both types of control variables must be considered.
When designing an experiment, it is important to establish both experimental and subject control variables. This will help ensure that any differences in the dependent variable are attributable to the independent variable and not some other factor.
