Visscher P M
Institute of Cell, Animal and Population Biology, University of Edinburgh, Scotland.
J Dairy Sci. 1992 May;75(5):1320-30. doi: 10.3168/jds.S0022-0302(92)77883-7.
Statistical power of likelihood ratio tests was investigated for detection of heterogeneous variances and intraclass correlation in balanced half-sib designs. Powers of likelihood ratio tests were obtained from simulations. For half-sib designs of sires nested within herds, true intraclass correlations and phenotypic variances, and estimates thereof, were repeatedly sampled, and likelihood ratio tests were conducted. The power for detecting heterogeneity of intraclass correlations was low, but the power for detecting heterogeneous phenotypic variances was nearly always 100%. For balanced cross-classified designs, sires had progeny in all herds, and data were simulated by assuming that heterogeneity of between- and within-sire components was the result of a herd-dependent scale effect. Using this model, the power to detect heterogeneous between-sire components was substantially higher than the corresponding power to detect heterogeneous intraclass correlations in the nested design. It seems unlikely that reliable inference about heterogeneity of genetic variances or heritabilities between individual herds from daily cattle field data can be made.
研究了似然比检验在平衡半同胞设计中检测异质方差和组内相关的统计功效。似然比检验的功效通过模拟获得。对于父本嵌套在畜群中的半同胞设计，反复抽取真实的组内相关和表型方差及其估计值，并进行似然比检验。检测组内相关异质性的功效较低，但检测异质表型方差的功效几乎总是100%。对于平衡交叉分类设计，父本在所有畜群中都有后代，通过假设父本间和父本内成分的异质性是畜群依赖尺度效应的结果来模拟数据。使用该模型，检测父本间异质成分的功效显著高于嵌套设计中检测组内相关异质性的相应功效。从日常牛场数据中对个体畜群间遗传方差或遗传力的异质性进行可靠推断似乎不太可能。
