For the entire month of January 2011, the local domestic violence shelter ran a series of ads on the government access cable television channel. Th e director of the shelter hypothesized that the ads would bring more attention to the problem of domestic violence and make victims of domestic violence more aware of the shelter’s programs. The director has monthly data on the number of new clients. At the end of April 2011, the director asks you to come up with a research design to help assess whether the ads had an effect on the number of clients served.

(a) What type of research design would you use to test the hypothesis?

(b) The director has monthly figures for the number of clients served in 2010.

Are these data relevant for testing the above hypothesis? If so, why?