Properties of bias and variance of two multiallelic estimators of FST
Properties of bias and variance of two multiallelic estimators of FST
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DOI：
10.1006/tpbi.2000.1457
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发表时间：
2000-05-01
影响因子：
1.4
通讯作者：
Bonhomme, F
中科院分区：
文献类型：
--
作者：
Raufaste, N;Bonhomme, F
本研究比较了固定指数F-ST的两种估计量对单基因座多等位基因数据的理论和模拟性质。估计者分别是Weir和Cockerham((WC))和Robertson和Hill((RH))。这两个估计器都是双等位基因估计器的线性组合，它们在频繁和罕见等位基因的加权方式上有所不同。因此，就偏差和方差而言，它们的采样特性是不同的。在迁移漂移平衡的无限岛模型中，在一个多等位基因的情况下，我们解析地近似了两个估计量的偏差，并证明了(WC)几乎无偏，而(RH)负偏。因此，我们建议对后者的偏差进行修正。此外，我们重新检查了初始估计的方差的性质：由于它们的构造，它们的方差是最小的，每个方差在不同的参数范围内，(RH)对于低微分表现更好，(WC)对于高微分表现更好。这些理论性质通过模拟得到了证实，这表明我们对(RH)偏差的校正效果很好，并且不影响其对低微分的最小方差性质。因此，我们主张使用(WC)来表示高的分化程度，而使用(RH)来纠正我们的偏差，用于低或中等的分化程度。(C)2000年学术出版社。
This study compares theoretical and simulated properties of two estimators of fixation indices F-ST for multiallelic data from a single locus. The estimators are due to Weir and Cockerham ((WC)) and to Robertson and Hill ((RH)), respectively. Both estimators are linear combinations of biallelic estimators which differ in the way frequent and rare alleles are weighted. Consequently, their sampling properties differ as far as bias and variance are concerned. In the infinite island model at migration-drift equilibrium, in the case of one multiallelic locus, we analytically approximate the bias of the two estimators and show that (WC) is nearly unbiased, whereas (RH) is negatively biased. Hence, we propose a correction of bias of the latter. Moreover, we reexamine the properties of variance of the initial estimators: due to their construction, their variances are minimal, each over different parameter ranges, (RH) performing better for low differentiation and (WC) for high differentiation. These theoretical properties are confirmed by simulations, which show that our correction of bias of (RH) performs well and does not affect its property of minimal variance for low differentiation. Hence, we advocate the use of (WC) for high values of differentiation, and the use of (RH), with our correction of bias, for low or moderate differentiation. (C) 2000 Academic Press.