Statistical modelling

We shall now explore, a little more closely, different representations of the effect of age of dam on weaning weight. The DAMAGE and residual lines in the analysis of variance (see previous screen view) read:

Source of variation

d.f

s.s.

m.s.

v.r.
+DAMAGE7

6

445.076

74.179

15.09

Residual

683

3357.495

4.916

  

First, let us replace the seven factor levels for DAMAGE7 by a quadratic function. We can do this by inserting the following two lines into the GenStat Input Window obtained via File → New... and submitting them for execution.

CALCULATE DL=DAMAGE7
CALCULATE DQ=DL*DL

Alternatively we can use Spread → Calculate → Column... and insert the appropriate calculations there.

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