To increase strength and/or muscle mass, weight trainers will try different approaches. One approach is to apply an electrical impulse through a muscle as the person is lifting a weight. A researcher wants to determine if adding this electrical impulse increases the amount of weight a person
can lift. To conduct his research, he selects one hundred people, and randomly divides them into two groups. One group wears a device that
sends an electrical impulse through the muscle used to repeatedly lift a 5 pound weight. The other group lifts the same weight without the electrical
impulse. The researcher counts the number of repetitions until the subjects can no longer lift the weight. Is this an example of an observational
study or an experiment?