How do efficacy and effectiveness studies compare on validity?

Question

Quizplus · Accepted Answer

Efficacy studies are conducted under controlled laboratory conditions, which improve internal validity. However, these conditions may not reflect real-world situations, leading to a lack of external validity. On the other hand, effectiveness studies are conducted in real-world situations, improving external validity but making it difficult to control extraneous variables, leading to a potential lack of internal validity. Therefore, efficacy studies tend to have internal validity but lack external validity, while effectiveness studies tend to have external validity but lack internal validity.

How Do Efficacy and Effectiveness Studies Compare on Validity