|
Statistical modelling
The matrix of coefficients multiplied by the corresponding estimated variance component values gives the table of approximate stratum variances (equivalent to the residual mean squares in a least squares analysis of variance).
The matrix of coefficients shows that each ram sired on average just over 10 lambs. The RAM_ID stratum variance also includes a proportion (0.42) of the ewe variance component reflecting the fact that rams were mated to more than one ewe.
The 2.10 matrix coefficient for EWE_ID shows that ewes had an average of just over two offspring during the study. Since a ram was never mated to the same ewe twice, the ewe stratum variance is independent of ram (indicated by the 0.00 value for ram).
|
|
**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
|
|
|
