a. Use the following data on retail truck sales in the southern United States (TS), in thousands of dollars, to prepare a time-series decomposition forecast of TS for 2008Q1-2008Q4:

b. Evaluate your model in terms of fit and accuracy using RMSE.
c. Plot your forecast values of TS along with the actual values.
d. Compare the results from your time-series decomposition model with those obtained using a Winters' exponential smoothing model in terms of both fit and accuracy.

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Truck Sales Year Q2 Q3 Q4 1987 4,78,124 6,12,719 6,13,902 6,46,312 1988 7,12,170 8,21,845 7,84,493 7,25,615 1989 8,48,323 9,34,438 8,17,396 8,85,389 1990 8,94,359 11,26,400 9,46,504 9,47,141 1991 9,21,967 8,38,559 7,64,035 7,11,234 1992 6,34,427 5,68,758 5,32,143 4,96,188 1993 4,99,968 5,59,593 4,95,349 4,17,391 1994 5,97,296 6,05,965 5,16,1735,28,238 1995 5,82,202 7,22,965 6,63,528 7,40,694 1996 8,52,7749,79,159 8,28,721 8,77,681 1997 9,93,431 10,47,300 9,82,917 9,59,867 1998 9,01,757 10,95,580 10,98,730 9,32,177 1999 9,35,125 11,45,360 10,71,020 10,22,050 2000 11,39,130 2,52,900 11,16,670 10,99,110 2001 10,80,950 12,22,890 11,95,190 9,83,803 2002 10,85,270 11,72,960 10,81,380 9,21,370 2003 8,45,99210,44,490 10,28,720 9,22,831 2004 9,57,733 12,40,610 11,71,230 11,43,440 2005 11,45,370 14,93,980 13,28,300 13,50,470 2006 14,30,080 16,36,760 14,56,740 15,02,440 2007 14,38,96016,61,130 14,90,620 15,00,120