Answer Happy

In a Microsoft Word document, using the R statistical software package, provide answers for the following problems Consider monthly sales and advertising data for an automotive parts company (data set advert). a. Plot the data using autoplot. Why is it useful to set facets=TRUE? b. Fit a standard regression model yt = a + bxt + nt where yt denotes sales and It denotes advertising using the ts1m () function. c. Show that the residuals have significant autocorrelation. d. What difference does it make if you use the Arima function instead: Arima (advert[,"sales"], xreg=advert[,"advert"], order=c(0,0,0)) e. Refit the model using auto.arima (). How much difference does the error model make to the estimated parameters? What ARIMA model for the errors is selected? f. Check the residuals of the fitted model. g. Assuming the advertising budget for the next six months is exactly 10 units per month, produce and plot sales forecasts with prediction intervals for the next six months.