what are controlled variables

Control variables, also known as scientific constants, are experimental elements that are held constant and unchanged throughout the course of an investigation or research project. They are not of primary interest to the experimenter, but they are controlled because they could strongly influence experimental results if they were not held constant during the experiment. Control variables are used to assess the relationship between multiple variables by keeping some factors constant so that comparison can happen in an unbiased and transparent manner. Control variables can be controlled directly by holding them constant throughout a study, or they may be controlled indirectly through methods like randomization or statistical control. By controlling variables, researchers can prevent research biases like omitted variable bias from affecting their results.