Biglan Et Al

Multiple Choice

Biglan et al.(1996) studied whether store clerks in eight Oregon towns were willing to sell tobacco products to minors.They measured clerk behavior repeatedly over time,implemented a positive reinforcement intervention at different times in different towns,and usually found a drop in willingness to sell after implementing this intervention.What research methodology did they use?

A) multiple baseline design.
B) interrupted time-series design.
C) nonequivalent comparison group design.
D) both "a" and "b"