Agriculture Reference
In-Depth Information
Number of obs = 240 R-squared = 0.8428
Root MSE = 17.2671 Adj R-squared = 0.7877
Source | Partial SS df MS F Prob > F
------------+----------------------------------------------------
Model | 282950.468 62 4563.71722 15.31 0.0000
|
rep | 17324.2156 3 5774.73854 19.37 0.0000
fertility | 131797.332 4 32949.3331 110.51 0.0000
sowingdate | 91867.921 2 45933.9605 154.06 0.0000
variety | 4741.19086 3 1580.39695 5.30 0.0016
fertility#
sowingdate | 18378.6525 8 2297.33156 7.71 0.0000
fertility#
variety | 949.869152 12 79.1557626 0.27 0.9935
sowingdate#
variety | 14911.549 6 2485.25816 8.34 0.0000
fertility#
sowingdate# |
variety | 2979.73751 24 124.155729 0.42 0.9931
|
Residual | 52773.3384 177 298.154454
------------+----------------------------------------------------
Total | 335723.806 239 1404.70212
Looking at the results, all three factors (fertility, sowing date, and
variety) are significant; however, there also are significant interactions
for fertility × sowing date and variety × sowing date. Therefore, these
interactions should be examined more closely. To begin with, it may
be helpful to examine both the fertility and variety means over the
different sowing dates. To do this, enter the commands
table
fertility sowingdate,
contents
(
mean
wtlbs)
table
variety sowingdate,
contents
(
mean
wtlbs)
This results in the following output tables:
----------------------------------------------------
Fertility |
:0-200 | Sowing Date: 1-10/5/01, 2-10/15/01,
lbs/acre | 3-10/29/01
nitrogen | 5 Oct. 2001 15 Oct. 2001 29 Oct. 2001
----------+-----------------------------------------
0 | 9.68125 8.39 3.4625
50 | 72.6094 62.925 25.9562
100 | 82.2906 71.315 29.4312
150 | 96.8125 83.9 34.6125
200 | 91.9719 79.705 32.875
----------------------------------------------------
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