A researcher at a drug treatment center wanted to determine the best combination of treatments that wouldlead to more substance free days. This researcher believed there were two key factors in helping drugaddiction: type of treatment and type of counseling. The researcher was interested in either residential or outpatient treatment programs and either cognitive behavioral psychodynamic or client centered counseling approaches as new clients enrolled to the center they were randomly assigned to one of the six experimental groups. After three months treatment each client symptoms were measured