Professor Chapin Is Conducting Research on the Relationship Between Headache

Multiple Choice

Professor Chapin is conducting research on the relationship between headache medication and the amount of pain reduction that is experienced by his participants.He expects that the medication will be very effective,and lo and behold he finds that it is a highly effective drug! Which of the following might have been a problem for Professor Chapin's experiment?

A) random assignment
B) demand characteristics
C) the self-fulfilling prophecy
D) experimenter bias