Given the following data on Asian and European Share of U.S. Light Truck Sales(1990-2003):
Year t Percent
1990 1 16.4
1991 2 17.1
1992 3 14.3
1993 4 13.7
1994 5 14.2
1995 6 13.6
1996 7 13.6
1997 8 15.4
1998 9 16.2
1999 10 18.4
2000 11 21.2
2001 12 23.1
2002 13 23.9
2003 14 26.6
(a) Plot the market-share data.
(b) Describe the trend (if any) and discuss possible causes.
(c) Fit three trends (linear, exponential, quadratic).
(d) Which trend model is best, and why? If none is satisfactory, explain.
(e) Make a forecast for 2004 by using a trend model of your choice or a judgment forecast.