Mark Price, the new productions manager for Speakers and Company, needs to find out which variable most affects the demand for their line of stereo speakers. He is uncertain whether the unit price of the product or the effects of increased marketing are the main drivers in sales and wants to use regression analysis to figure out which factor drives more demand for their particular market Pertinent information was collected by an extensive marketing project that lasted over the past 10 years and was reduced to the data that follow YEAR 1998 1999 2009 2001 00 2002 2003 2004 00 2005 1002 2006 2007 2008 2009 SALES/UNIT (THOUSANDS) 409 700 900 1,300 1,150 1, 900 1,100 980 1,234 925 800 PRICE $/UNIT 289 215 211 210 215 2 200 200 225 L 207 207 220 211 227 245 ADVERTISING ($000) 600 835 1,100 1,400 1,200 1,300 909 900 1,100 700 900 700 690 a. Perform a regression analysis based on these data using Excel. (Negative values should be indicated by a minus sign. Round your answers to 4 decimal places.) bar Price + Advertising