Cell Phone Company a Adds a New Charge for Customers

Multiple Choice

Cell phone Company A adds a new charge for customers who use too much data each month; Company B does not have this charge. A marketing researcher is given access to the data usage records for both companies, starting 30 months before and ending 30 months after the charge was instituted. She found that excessive data usage declined dramatically for Company A's customers but that there was no reduction in data usage for Company B's customers. The researcher used a(n) ________ design for her study.

A) control series
B) multiple time series
C) nonequivalent control group pretest-posttest
D) patched-up quasi-experimental