Which variable is manipulated or tested in an experiment?

The independent variable is the factor that is purposely manipulated or changed in an experiment to assess its effects on other variables, primarily the dependent variable. By varying this element, researchers can observe how it influences the outcomes of the experiment, allowing them to establish cause-and-effect relationships.

In experimental design, the role of the independent variable is crucial because it enables scientists to formulate hypotheses and test their predictions rigorously. For instance, if a researcher is studying the impact of different light conditions on plant growth, the light condition constitutes the independent variable.

In contrast, the dependent variable is measured as a response to changes in the independent variable, while control variables remain constant to ensure that any observed changes can be attributed solely to the manipulation of the independent variable. The response variable typically refers to the same concept as the dependent variable, and control variables are adjustments made to eliminate external influences on the experiment's outcome.