Control variable

For control variables in mathematics, see independent variable.

Control variables are those variables that are not changed throughout the trials in an experiment because the experimenter is not interested in the effect of that variable being changed for that particular experiment. (In other words, control variables are extraneous factors, possibly affecting the experiment, that are kept constant so as to minimize their effects on the outcome.) An example of a control variable in an experiment might be keeping the pressure constant in an experiment designed to test the effects of temperature on bacterial growth.

In a scientific experiment, the controlled variable never changes; it is the same for every setup.

Examples

Area of a container- For example, in a evaporation experiment, the area must be the same. Temperature- The temperature, if changed, and is NOT the independant variable could change how a chemical reacts, therefore affecting the results

See also

• Scientific Method