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United States Department of Agriculture

Agricultural Research Service

Title: Adjustment for Heterogeneous Genetic and Non-Genetic (Co)variance Structures on Test-Day Models Using a Transformation on Random Regression Effect Regressors

Authors
item Gengler, N - GEMBLOUX AGRIC UNIV
item Wiggans, George

Submitted to: Interbull Annual Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 26, 2002
Publication Date: N/A

Interpretive Summary: A method of accounting for differences in variation in components of test-day milk production records was developed. This method could improve the accuracy of genetic evaluations. A random regression model is used to analyze the data, then a transformation is applied to the random regression coefficients. Comparing evaluations with and without this transformation, rankings of animals were similar but some rerankings occurred. A correlation analysis showed a reduction in the effect of production level on the variation in regression coefficients indicating the success of the ransformation. The method suggests a number of innovative solutions to problems related to heterogeneous variance structures.

Technical Abstract: A method of accounting for differences in variation in components of test-day milk production records was developed. This method could improve the accuracy of genetic evaluations. A random regression model is used to analyze the data, then a transformation is applied to the random regression coefficients. Comparing evaluations with and without this transformation, rankings of animals were similar but some re-rankings occurred. A correlation analysis showed a reduction in the effect of production level on the variation in regression coefficients indicating the success of the transformation. The method suggests a number of innovative solutions to problems related to heterogeneous variance structures.

Last Modified: 10/24/2014
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