Carlos is conducting an investigation in which he changes one variable and measures how it affects another. He also has one group that does not receive the factor being tested.

What type of investigation is Carlos conducting?

Carlos is conducting a controlled experiment. A controlled experiment is a scientific test where only one variable is changed and there is a group of subjects (named the control group) that is not receiving the factor that is being tested. The group of subjects receiving a treatment or the factor which is being tested is called the experimental group. The variable which is different between the control and the experimental group is the independent variable. The dependent variable depends on the independent variable and represents the response that we observe as an outcome of our experiment.