The Improvement Rate in a Group of Patients Receiving a New

Multiple Choice

The improvement rate in a group of patients receiving a new behavioral therapy for obsessive-compulsive disorder is 62 percent.The improvement in the control group,who received no therapy,is 32 percent.The improvement in the control group is most likely due to:

A) the placebo effect.
B) experimenter bias.
C) participant bias.
D) inadequate experimental controls.