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How to set the initial value of asreml, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain for you in detail, people with this need can come to learn, I hope you can gain something.

1. Background

A friend asked me how to fix the initial value of asreml, which is now divided into single traits and multiple traits.

Why should the initial value be fixed:

1. Because the population is small and the estimated variance components are not accurate, it is necessary to set the initial value manually and solve it directly.

2. For some group data, the estimated variance components do not converge, so the initial values need to be fixed manually.

Why set the initial value:

1. Estimate from scratch, the running time of the model is longer, and the iterative convergence speed is faster by manually setting the initial value according to the prior information.

2. In multi-character analysis, the model is not easy to converge, and it is easier to converge and iterate by setting the initial value manually.

two。 Set initial value and fixed initial value of single character

Take the data harvey included in the asreml package as an example to demonstrate.

> library (asreml)

> data (harvey)

> head (harvey)

Calf Sire Dam Line ageOfDam y1 y2 y3

1 101 Sire_1 01 3 192 390 224

2 102 Sire_1 0 1 3 154 403 265

3 103 Sire_1 0 1 4 185 432 241

4 104 Sire_1 0 1 4 183 457 225

5 105 Sire_1 0 1 5 186 483 258

6 106 Sire_1 0 1 5 177 469 267

The first three data are classified as pedigree data, Line is a fixed factor, ageOfDam is a covariable, and y1menjiny2 and y3 are three traits.

2.1 run single trait animal model # calculate An inverse matrix

Ainv

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