Solutions Statistics

(a) Plot the data on U.S. general aviation shipments. (b) Describe the pattern and discuss possible

Question: (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 1992-2003 only. Would a fitted trend be helpful in making a prediction for 2004? (e) Fit a trend model of your choice to the 1992-2003 data. (f) Make a forecast for 2004, using either the fitted trend model or a judgment forecast. Why is it best to ignore earlier years in this data set?

U.S. Manufactured General Aviation Shipments, 1966-2003
Year	Planes	Year	Planes	Year	Planes	Year	Planes
1966	15,587	1976	15,451	1986	1,495	1996	1,053
1967	13,484	1977	16,904	1987	1,085	1997	1,482
1968	13,556	1978	17,811	1988	1,143	1998	2,115
1969	12,407	1979	17,048	1989	1,535	1999	2,421
1970	7,277	1980	11,877	1990	1,134	2000	2,714
1971	7,346	1981	9,457	1991	1,021	2001	2,538
1972	9,774	1982	4,266	1992	856	2002	2,169
1973	13,646	1983	2,691	1993	870	2003	2,090
1974	14,166	1984	2,431	1994	881
1975	14,056	1985	2,029	1995	1,028