Agriculture Reference
In-Depth Information
4
2
0
-2
-4
90
92
94 96
Fitted Values
98
100
4
2
0
-2
-4
4.5
5
Body Weight for Hens
5.5
6
Figure 10.3
The fitted value versus residuals and predictor versus residuals graphs for the hen
data regression.
Figure 10.4 shows the fitted values versus the residuals (the predic-
tor versus residuals would look the same with this model). Notice the
points are above the 0 line near 4,500 and 7,000 on the
x
-axis and
below the 0 line in the center. This dataset actually has two different
varieties that perform quite differently. To see this graphically enter
the following command:
twoway
(scatter
yield tiller
in
1
/
8
) (lfit
yield
tiller
in
1
/
8
)
(scatter
yield tiller
in
9
/
16
)
(lfit
yield tiller
in
9
/
16
)
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