Question

Analyze: There is considerable debate within your firm concerning the effect of advertising on sales. The marketing department believes advertising has a large positive effect; others are not so sure. For instance, the production and technical staffs believe the quality of the product itself largely determines sales. To clarify the debate, you have gathered the attached data for the last 24 quarters. Also refer to an Introduction to Regression in MS-Excel as needed.

e. Because of a recent, new marketing plan, some at your firm argue that the effectiveness of advertising has changed over time and especially 2012-2013 compared to 2016-2017. Using dummy independent variables in your regression, test this hypothesis and take a justifiable stand on the argument.

Year	Quarter	Unit Sales	Advertising	Dum12_13	Dum16_17
2012	1	120	39	1	0
2012	2	115	36	1	0
2012	3	97	38	1	0
2012	4	118	39	1	0
2013	1	88	23	1	0
2013	2	63	22	1	0
2013	3	82	40	1	0
2013	4	80	42	1	0
2014	1	95	36	0	0
2014	2	106	49	0	0
2014	3	105	66	0	0
2014	4	136	65	0	0
2015	1	122	51	0	0
2015	2	112	56	0	0
2015	3	116	60	0	0
2015	4	104	51	0	0
2016	1	137	55	0	1
2016	2	114	47	0	1
2016	3	104	50	0	1
2016	4	122	47	0	1
2017	1	108	32	0	1
2017	2	94	41	0	1
2017	3	98	45	0	1
2017	4	104	34	0	1

Answer 1