Control variables are factors or elements in a research study or experiment that are kept constant or unchanged throughout the investigation. They are not the primary focus of the research but are controlled because they could influence the outcome of the study. By holding these variables steady, researchers ensure that any observed effects on the dependent variable are due to the manipulation of the independent variable, rather than other extraneous factors. This practice enhances the internal validity of the study, preventing confounding variables from biasing the results.
For example, in a plant growth experiment testing different fertilizers, factors like soil moisture, sunlight, and temperature are controlled variables. Keeping these constant allows researchers to attribute differences in plant growth to the fertilizers rather than environmental variations.
Control variables can be directly controlled by keeping conditions the same or indirectly controlled through statistical methods or randomization, especially in non-experimental studies where direct control is not feasible.
