Jayshawn is conducting a research study for his psychology course. He is studying whether playing violent video games causes children to engage in aggressive acts afterwards. He randomly assigns children to two conditions: one group receives a violent video game to play for a half-hour and another group of children receives no video game to play. He then measures their tendency to act aggressively by having them play with a BOBO doll (punching bag) and recording their aggression toward the object. Jayshawn is conducting an Blank.