Joaquim wants to determine whether cognitive therapy is effective in treating depression. He measures the change recommendations to implement, and then measuring depression levels in a posttest. Joaquim cone invalid?
A. Joaquim should have had the participants change only one behavior at a time.
B. Joaquim should have used more participants.
C. Joaquim should have studied other types of therapy as well.
D. Joaquim should have used a control group.
E. Joaquim should have operationally defined depression better
