A clinical psychologist has developed a new form of psychotherapy to treat a particular personality disorder. in order to test its effectiveness, a group of people with the personality disorder is selected to receive the therapy for 8 weeks. a second group of people with the disorder is also created, but this group receives no therapy at all. at the end of the 8 weeks, the mental health of people in both groups is assessed to evaluate the new psychotherapy. in this study, the people who did not receive any therapy would be in the: