Advertising A local financial advisor places advertisements in the local newspaper as well as on local cable television programs. Her success depends on how many callbacks these ads generate. She wants to know if the advertising is cost effective and has data for 83 recent weeks. These are not consecutive (holidays are omitted), but the data are presented in time order.
(a) From timeplots of the amounts spent for print and cable advertising and the number of call-backs, describe recent patterns in her business.
(b) The slope b1 in the simple regression of the number of calls on the cost of printed ads is larger than b1 in the simple regression of calls on the cost of cable ads. Because of this, she plans to devote more advertising to cable ads. Do you agree? Use a multiple regression of calls on both types of advertising.
(c) Does the multiple regression in (b) satisfy the conditions of the MRM?
(d) A colleague claims that advertising does not matter. She’s just benefiting from trends in financial behavior. Do you agree? Use another multiple regression to decide.