Which statement defines the independent variable?

• A. The dependent variable is the outcome measured.
• B. The random allocation of participants is used to ensure group equivalence.
• C. The independent variable is the factor deliberately manipulated; example: type of instruction method (video vs text).
• D. The control condition is used to minimize placebo effects.

Answer: (C)

The independent variable is the factor deliberately manipulated by the researcher to observe its effect on the outcome. In the example, changing the instruction method (video versus text) is the manipulation being tested to see if it influences learning. This direct manipulation is what lets us attribute any differences in the dependent variable to the chosen method. The dependent variable is what you measure as the outcome. Random allocation helps keep groups similar at the start, reducing pre-existing differences. The control condition provides a baseline to compare against and helps account for placebo or other non-specific effects.