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发表于 2009-12-25 22:05:06
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本帖最后由 牧童 于 2009-12-25 22:28 编辑
Whilst the part of the coeffcient matrix C arising from the covariances among random effects is sparser than in the corresponding MME for (1), it has to be borne in mind that Z *and W* can be considerably denser than matrices Z and W, although there is a ‘trade-off’ as the covariance matrices among random effects proportional to identity matrices generate fewer links between random effects levels. Hence computational savings in manipulating the MME arise mainly from the reduction in the number of equations when mA< kA or mR< kR.
根据大家的回复,我整理一下
同时,系数矩阵C中与随机效应间的协方差对应的那一部分,要比公式(1)的MME中相应的这一部分稀疏,必需牢记矩阵Z*和W*比矩阵Z和W要稠密得多,虽然,由于随机效应间的协方差矩阵与单位矩阵成比例并且随机效应水平间的联系更少,但是仍然存在(信息的)交换。所以,在计算MME时节约的计算量主要原因是mA<KA或mR<kR时方程个数的减少。
不知道上端翻译还有什么错误?或者更好懂的译文?请大家继续指正~~~~~~~~~~~~~ |
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