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wombat:faqshow [2018/09/13] kmeyer [Standard errors for estimates of fixed and random effects fitted] |
wombat:faqshow [2018/09/13] (current) kmeyer [Standard errors for estimates of fixed and random effects fitted] |
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| - If only a **small** proportion of dams are unknown (less than 5% or so), you could replace the missing dam codes by some dummy code, assigning a different fictitious dam to each animal with unknown dam. | - If only a **small** proportion of dams are unknown (less than 5% or so), you could replace the missing dam codes by some dummy code, assigning a different fictitious dam to each animal with unknown dam. | ||
| N.B. Even if all animals in the data have known dams, you may have animals in the pedigree with unknown dams. If you wish to fit a maternal genetic effect, you will then similarly need to assign dummy dam codes for all unknown dams, i.e. the third column in the pedigree file cannot contain any zeros. Again, your analysis will work best if this proportion of dams is relatively small. | N.B. Even if all animals in the data have known dams, you may have animals in the pedigree with unknown dams. If you wish to fit a maternal genetic effect, you will then similarly need to assign dummy dam codes for all unknown dams, i.e. the third column in the pedigree file cannot contain any zeros. Again, your analysis will work best if this proportion of dams is relatively small. | ||
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| - | =?=== Standard errors for estimates of fixed and random effects fitted ==== | ||
| - | * **Q:** I have run a standard variance component analysis and found the solutions for effects fitted in the model. However, corresponding standard errors are missing - how do I get them? | ||
| - | * **A:** In a mixed model analysis, approximate lower bound standard errors are obtained from the diagonal elements of the inverse of the coefficient matrix. The default method for variance component estimation is the "average informatiom" algorithm. The implementation in WOMBAT does not involve inversion of the coefficient matrix - hence standard errors are not simply a by-product. | ||
| - | \\ You can enforce calculation of standard errors by simply adding the option ''FORCE-SE'' in a ''SPECIAL'' block at the end of the parameter file. | ||
| - | <WRAP column 25% :en> | ||
| - | <code > | ||
| - | SPECIAL | ||
| - | FORCE-SE | ||
| - | END | ||
| - | </code> | ||
| - | </WRAP> | ||
