(a) Plot the data on U.S. general aviation shipments.
(b) Describe the pattern and discuss possible causes.
(c) Would a fitted trend be helpful? Explain.
(d) Make a similar graph for 1993­2008 only. Would a fitted trend be helpful in making a prediction for 2009?
(e) Fit a trend model of your choice to the 1993­2008 data.
(f) Make a forecast for 2009, using either a fitted trend model or a judgment forecast.
(g) Might it be best to ignore earlier years in this data set?

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U.S. Manufactured General Aviation Shipments, 1977-2008 Year Planes Y Planes Year Planes Year Planes 1977 16,904 1985 2,029 1993 1978 17,8 98 4 1994 1979 17,048 97 08 995 1,077 2003 2,137 1980 11,877 1988 1,212 1996 2 2355 1981 9457 1989 1,535 1997 1,549 2005 2,857 1982 4,266 1990 , 998 2,200 2006 3,147 1983 2,691 99 02 1999 2,504 007 3,279 1984 2,431 1992 964 200 2,634 928 2002 2,207 5 2 941 2000 2,816 2008 3,079