The type of experiment that tests a variable and measures its effect is called a controlled experiment. In a controlled experiment, the researcher manipulates one variable, known as the independent variable, while keeping all other variables constant. The effect of the independent variable on another variable, known as the dependent variable, is then measured and analyzed.
Controlled experiments are designed to establish cause-and-effect relationships between variables. By controlling for other factors and isolating the impact of the independent variable, researchers can determine whether changes in the independent variable directly influence the dependent variable. This type of experiment allows for rigorous testing and evaluation of hypotheses and helps in drawing meaningful conclusions about the relationship between variables.