A new cream was developed to reduce the irritation caused by poison ivy. To test the effectiveness, researchers put an ad online asking for volunteers to participate in the study. One hundred subjects replied, and they were informed that one group would receive the new cream and the other group would receive a cream with no active ingredient. All 100 subjects were exposed to poison ivy. Fifty were then assigned to the group with the new cream, and 50 were assigned to the group with the cream with no active ingredient. After three days, the subjects’ level of irritation was measured. Of the 50 subjects that were assigned to the cream with no active ingredient, 15 stated they had less irritation. What is this called?

placebo
control group
placebo effect
placebo control