Question 132363: Please help me. I need answer to this question desperately. Please kindly help me.
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? Airplanes
U.S. Manufactured General Aviation Shipments, 1966–2003
Year Planes
1966 15,587
1967 13,484
1968 13,556
1969 12,407
1970 7,277
1971 7,346
1972 9,774
1973 13,646
1974 14,166
1975 14,056
1976 15,451
1977 16,904
1978 17,811
1979 17,048
1980 11,877
1981 9,457
1982 4,266
1983 2,691
1984 2,431
1985 2,029
1986 1,495
1987 1,085
1988 1,143
1989 1,535
1990 1,134
1991 1,021
1992 856
1993 870
1994 881
1995 1,028
1996 1,053
1997 1,482
1998 2,115
1999 2,421
2000 2,714
2001 2,538
2002 2,169
2003 2,090
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! a) Plot the data on U.S. general aviation shipments.
You can do that with a dot-plot.
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(b) Describe the pattern and discuss possible causes.
There is a definite downward trend in number of shipments.
Possible causes are: price of gasoline to the buyer; price of insurance
due to terroism.
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(c) Would a fitted trend be helpful? Explain.
While there is a consistent downward trend the quantitative
changes are not consistent. A fitted trend would not be helpful.
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(d) Make a similar graph for 1992–2003 only. Would a fitted trend be helpful in making a prediction for 2004?
1992 856
1993 870
1994 881
1995 1,028
1996 1,053
1997 1,482
1998 2,115
1999 2,421
2000 2,714
2001 2,538
2002 2,169
2003 2,090
It appears that 2004 should have close to 2000 shipments.
A fitted trend might be helpful as the pattern is gradually
up to a max at year 2000, then down.
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(e) Fit a trend model of your choice to the 1992–2003 data.
Using a Quadratic Regression function on a TI calculator I get:
y = -12.195..x^2+357.867x -167.92
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(f) Make a forecast for 2004, using either the fitted trend model or a judgment forecast.
Using the trend model I get: 2452
Using judgment forecast: I think 2000
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Why is it best to ignore earlier years in this data set?
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I'll leave that to you.
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Cheers,
Stan H.
Airplanes U.S. Manufactured General Aviation Shipments, 1966–2003
Year Planes
1966 15,587
1967 13,484
1968 13,556
1969 12,407
1970 7,277
1971 7,346
1972 9,774
1973 13,646
1974 14,166
1975 14,056
1976 15,451
1977 16,904
1978 17,811
1979 17,048
1980 11,877
1981 9,457
1982 4,266
1983 2,691
1984 2,431
1985 2,029
1986 1,495
1987 1,085
1988 1,143
1989 1,535
1990 1,134
1991 1,021
1992 856
1993 870
1994 881
1995 1,028
1996 1,053
1997 1,482
1998 2,115
1999 2,421
2000 2,714
2001 2,538
2002 2,169
2003 2,090
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