Walmart grew rapidly in the years leading up to the financial crisis. Here is the monthly revenue ($ Billion) for Walmart from November 2003 to January 2007.

a) What components of a time series do you see in this timeplot? Here€™s a regression model fit using dummy variables for months and a Time variable that counts from 1 for the first data value in the series.

b) Interpret the coefficient of Time.
c) Interpret the coefficient of Dec.
d) What revenue would you predict for Walmart in February 2007 (the 40th month in this series)?
e) What does it mean that the coefficient for Oct is the only negative coefficient in the model?

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25 Month Nov May Nov May Nov May Nov Year 2003 2004 2005 2006 Dependent variable is: WM Rev R squared-94.3% R squared (adjusted) 91.6% s# 1.121 with 39-13# 26 degrees of freedom Variable Coeff Intercept 12.0322 0.6562 Time Feb Mar Apr May SE (Coeff) t-ratio P-value <0.0001 8.93 <0.0001 0.1013 0.0027 0.0609 0.3191 <0.0001 0.9020 0.6164 0.0009 0.7998 0.0262 0.0001 18.3 un Jul Aug Sep Oct Nov Dec 0.145241 0.0163 1.46096 0.8599 2.84671 .8585 1.67981 0.8574 0.970232 0,8567 4.99999 0.8562 0.106417 0.8560 0,434176 0,8562 3.25327 0.8567 -0.219640 0.8574 .97023 0.7932 0.7927 1.70 3,32 1.96 1.02 5.94 0.124 0.507 3.90 -0.256 2.36 11.5625 14.6