Which variable is manipulated by the researcher in an experiment?

In an experiment, the researcher manipulates the independent variable to observe how it affects the dependent variable. The independent variable is the factor that is changed or controlled in a scientific experiment to test its effects on the outcome. This manipulation allows researchers to establish cause-and-effect relationships between the independent variable and the dependent variable.

In contrast, the dependent variable is what is measured in the experiment and is expected to change as a result of manipulations of the independent variable. Confounding variables are those that could potentially influence the results and introduce bias, but they are not manipulated by the researcher. Extraneous variables are any variables other than the independent variable that may have an effect on the dependent variable, and while they can be controlled for, they are not manipulated. Therefore, the role of manipulating the variable lies with the independent variable, making it crucial for experimental design and the integrity of the results.