In program evaluation, what is the difference between efficacy and effectiveness?

In program evaluation, what is the difference between efficacy and effectiveness?

• A. Efficacy is success under ideal, controlled conditions; effectiveness is success in real-world settings.
• B. Efficacy is about financial cost; effectiveness is about patient satisfaction.
• C. Efficacy is measured in the field; effectiveness in the lab.
• D. Efficacy is success under ideal, controlled conditions; effectiveness is success in real-world settings.

Answer: (D)