Diffusion or imitation of the program by people in a non-treatment control group tends to
A) make an effective program look less effective than it is.
B) make an ineffective program look more effective than it is.
C) make a good program appear to have a negative impact.
D) nullify the effects of attrition from control groups.

Question

Quizplus · Accepted Answer

Diffusion or imitation of the program by people in a non-treatment control group can lead to the control group receiving some benefit from the program, which can make the program appear less effective than it actually is. This is known as the "contamination effect."

Diffusion or Imitation of the Program by People in a Non-Treatment