Statistical modelling

From the results of the two analyses we can break down the sum of squares of 445.076 for DAMAGE7 in the first analysis into components for DL and DQ (101.581 and 308.044 in the second analysis - see previous screen ) and a remainder (445.076 - 101.581 - 308.044 = 35.451). Presenting these values together with the residual line we get:
Source of variation

d.f

s.s

m.s.

v.r.
DAMAGE7

6

445.076

74.179

  
DL

1

101.581

101.581

  
DQ

1

308.044

308.044

  
Remainder

4

35.451

8.863

1.80

Residual

683

3357.495

4.916

  

The 'Remainder' term, which represents the DAMAGE7 variation not accounted for by the quadratic function, is not significant (VR = 1.80). Since the size of this remaining variation is not statistically significant it can be deduced that the quadratic fit is a good one. We can also argue that it is not necessary to add a cubic term to the polynomial equation and decide not to do so.

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