What type of variable is manipulated in an experiment?

In an experiment, the type of variable that is manipulated by the researcher is known as the independent variable. This variable is intentionally changed or altered to observe how it affects other variables within the experiment, particularly the dependent variable, which is the outcome being measured.

Understanding the role of the independent variable is fundamental in experimental design. By manipulating this variable, researchers are able to determine cause-and-effect relationships. For instance, if a music therapist changes the type of music used in a session to see its impact on client engagement, the type of music becomes the independent variable.

The other types of variables listed serve different roles in research. For example, the dependent variable relies on the changes made to the independent variable; controlled variables remain constant to ensure that the experiment measures only the effects of the independent variable. Quantitative variables refer to numerical data that can be measured and analyzed but do not directly indicate manipulation within the context of an experiment.