To understand the effectiveness of its marketing strategies, ABC Co. tracks its adver- tisement expenditures and sales in every marketing campaign. There are 3 variables contained in the dataset provided by ABC. i Influencer type Macro or Nano ii Sales ($ thousands) Sales from the marketing campaign iii Social media ($ thousands) Advertisement expenditures on social media of the marketing campaign (a) [5 marks] Estimate a multiple linear regression model in which the dependent vari- able is "Sales and the independent variables are "Influencer type and Social media. What is the estimated regression model? For example, write: Sales = 0.1 +0.2 x Macro + 0.3 x Social Media (b) [5 marks] Examine the estimated coefficients from the regression model in (a). Are they statistically significant at the 5% level? How do you interpret them? (c) [5 marks] The marketing manager believes that Macro influencers provide a greater return to sales per advertisement dollar spent. Estimate a multiple linear regression model to test whether the empirical data supports his beliefs. Write down the estimated regression model. Hint: You need to construct a new independent variable. (d) [5 marks] Do the estimated results of the regression model in (c) support the mar- keting manager's belief? Why? Sales Social Media 7.13 363.19 422.80 3.67 237.19 3.88 354.40 2.83 Influencer type Macro Macro Macro Macro Macro Macro Macro Macro Macro Macro 339.58 2.19 3.42 295.67 194.71 2.59 332.95 5.61 0.68 122.92 1.59 99.57 167.87 163.35 0.04 0.46 260.01 1.73 Macro Macro Macro Macro Macro Macro 129.47 2.44 353.10 289.14 356.18 6.11 4.59 3.21 Macro 201.69 3.37 147.48 2.94 0.47 61.36 180.79 159.42 Nano Nano Nano Nano Nano Nano Nano Nano Nano Nano Nano 4.79 3.32 0.95 116.34 7.02 2.09 2.35 0.57 310.22 242.04 210.73 169.23 77.39 179.14 173.35 167.97 2.13 Nano 0.66 Nano Nano 3.61 5.33