13. Perform multiple linear regression analysis with Period, DIFF, and ADV as independent variables. Formulate the equation and find MAD. Which variable is the most significant predictor of demand? Rank the independent variables based on their degree of contribution to the model. Observe significant F, R, R-squared, and p-values and explain.

14. Use the model obtained in part 13 and make forecasts for the following months. Make sure to seasonalize final forecasts.

Period Price AIP ADV

Jan. 2023 $9.20 $6.95 $14.5

Feb. 2023 $9.4 $6.60 $15.3

Mar. 2023 $9.10 $7.05 $15.2

15- Provide a case conclusion based on above analysis.