In a lab experiment, which statement best describes the independent variable?

In a lab experiment, which statement best describes the independent variable?

• A. The variable that is randomly assigned to manipulate the outcome
• B. The variable manipulated by the researcher to produce a change in the DV
• C. The variable measured to assess the effect
• D. The variable kept constant to prevent confounding

Answer: (B)

The independent variable is the variable the researcher deliberately changes to test its effect on the outcome. It is the cause the experimenter manipulates to see if it produces a change in the dependent variable. For example, if you’re investigating whether sleep duration affects test performance, sleep duration is the IV because you control and vary how much sleep participants get. All other factors are kept constant as controls to prevent confounding results. The dependent variable is what you measure to see the effect, such as test performance in this example. Random assignment helps ensure groups are comparable, but it isn’t the manipulated variable itself.

The independent variable is the variable the researcher deliberately changes to test its effect on the outcome. It is the cause the experimenter manipulates to see if it produces a change in the dependent variable. For example, if you’re investigating whether sleep duration affects test performance, sleep duration is the IV because you control and vary how much sleep participants get. All other factors are kept constant as controls to prevent confounding results. The dependent variable is what you measure to see the effect, such as test performance in this example. Random assignment helps ensure groups are comparable, but it isn’t the manipulated variable itself.