To Study the Effectiveness of a New Anti-Anxiety Drug, Researchers

Multiple Choice

To study the effectiveness of a new anti-anxiety drug, researchers randomly assign equally anxious people to two groups, one getting Drug X and the other getting no drug. The researchers mistakenly conclude that Drug X works because people in the drug group show fewer signs of anxiety than the others. What is the mistake?

A) They never introduced an independent variable.
B) They did not create a placebo control group.
C) They never did a pretest of anxiety symptoms.
D) They did not operationally define what the experimental group was.