From 1990 to 2000, the American Medical Association conducted a
study on patient fatigue and medication for depression. Fatigue
decreased with each increase in dosage, but then also decreased with
every decrease in dosage. If it is assumed the patients knew a study
was in progress, what is this an example of? (4 points)
The effect of a treatment unit
The placebo effect
The control group effect
Sampling error
Voluntary response bias