A study was conducted to see whether participants would ignore a sign that​ said, "Elevator may stick between floors. Use the​ stairs." Those who used the stairs were said to be​ compliant, and those who used the elevator were said to be noncompliant. There were three possible​ situations, two of which involved confederates. A confederate is a person who is secretly working with the experimenter. In the first​ situation, there was no confederate. In the second​ situation, there was a compliant confederate​ (one who used the​ stairs), and in the third​ situation, there was a noncompliant confederate​ (one who used the​ elevator). The subjects tended to imitate the confederates. What more do you need to know about the study to determine whether the presence or absence of a confederate causes a change in the compliance of​ subjects?