Statistical
modelling
The dialog box below
shows how to produce the mixed
model analysis for lamb weaning weight with ram and ewe defined as
random effects.
Note that since each ram and ewe is identified with its
own unique code (see CS4Data),
GenStat recognises that the random components are to be calculated
within breed. Had ram and ewe been coded within breed (e.g. each breed with
cumulative integers from 1 onwards) the random terms
would have had to be specified as RAM_BRD.RAM_ID, EWE_BRD.EWE_ID,
interpreted as ram within ram breed and ewe within ewe breed,
respectively.
|
|
**Estimated Variance Components **
| Random
term |
Component |
S.e. |
| RAM_ID |
0.067 |
0.089 |
| EWE_ID |
1.457 |
0.283 |
***
Residual variance model ***
|
Parameter
|
Estimate
|
S.e.
|
|
Sigma2
|
3.427
|
0.266
|
**Approximate stratum variances ***
| |
|
Effective
d.f.
|
| RAM_ID |
4.733
|
57.66
|
| EWE_ID |
6.490
|
297.74
|
| *units* |
3.427
|
332.60
|
* Matrix of
coefficients of components for each stratum
| RAM_ID |
10.31
|
0.42
|
1.00
|
| EWE_ID |
0.00
|
2.10
|
1.00
|
| *units* |
0.00
|
0.00
|
1.00
|
*** Deviance: -2*Log-Likelihood ***
| Deviance |
d.f. |
| 1817.10 |
685 |
***
Wald tests for fixed effects ***
| Fixed
term |
Wald
statistic |
d.f.
|
Wald/d.f.
|
Chi-sq
prob
|
| *
Sequentially adding terms to fixed model |
| YEAR |
230.32
|
5
|
46.06
|
<0.001
|
| SEX |
9.66
|
1
|
9.66
|
0.002
|
| AGEWEAN |
63.84
|
1
|
63.84
|
<0.001
|
| DL |
30.44
|
1
|
30.44
|
<0.001
|
| DQ |
78.41
|
1
|
78.41
|
<0.001
|
| RAM_BRD |
6.64
|
1
|
6.64
|
0.010
|
| EWE_BRD |
2.91
|
1
|
2.91
|
0.088
|
|
|
