协方差

Objective To study genetic variance component model of qualitative traits with covariates in nuclear family, and to analyze the effects of genetic factors and environmental factors.

目的 研究核心家系中带协变量的质量性状的遗传方差分量模型，定量地评价遗传因素和环境因素对质量性状的作用。

Since in some instance, the variance of response variable might be changeable along withthe alteration of explanatory variable, in the procedure of model constructing, a fixedeffects model should be considered firstly, then the random effects model or randomcoefficient model when necessary. The best fit model should be chosen by comparing thealterations of between-study variance and residual variance, as well as their relationshipswith covariates.

基于各研究中因变量与自变量间的曲线形状可能存在较大差异，建模时可依次考虑固定效应模型、随机效应模型和带协变量的随机系数模型，并观察研究水平的方差与残差方差的变化，以及与协变量的关系，从而选择最优模型。

The efficiency problem on the electricity futures market is systematically investigated from the three aspects, i.e., the market efficiency, the price discovery function and the hedge function by means of the. cointergration technique, the variance ratio and the Granger causality test methods, etc.

从电力期货市场的有效性、价格发现功能效率和套期保值功能效率三个方面，借助协整技术、方差比检验、Granger因果检验等，系统地研究了电力期货市场的效率问题。

Then, separately through the variance ratio method and the cointegeration approach, tests the efficiency and the unbiasbility of price discovery function, thereby identifies the realization degree of China's grain futures market price discovery function.

然后，分别用方差比检验法和协整关系检验法实证检验了我国粮食期货市场价格发现功能的有效性和无偏性，从而检验我国粮食期货市场价格发现功能的实现程度。

A reduced order fit involved less parameters and smoothes out differences in estimates of covariances.

降价配合涉及的参数较少，同时可以缓和协方差估值间的差异。

In which a security's required return depends on its expected liquidity as well as on the covariances of its own return and liquidity with the market return and liquidity.

证券的收益依赖于它的期望流动性及其与收益之间的协方差。

While defined in terms of variances and covariances, PCA is usually applied to standardized data since the results are sensitive to the often arbitrary choices of units of measurement used in a study.

就定义差异变量和协方差而言，PCA分析前通常要先标准化处理数据，因为，PCA对任意选择研究中的计量单元是敏感的。

In this paper a method of using input - output sequences in a real system to identify a constant, multi-variable and stochastic linear system having unknown dimensions, system matrices and noise covariances is developed.

本文提出了利用实际系统的输入—输出试验数据，辨识具有未知维、参数阵和噪声协方差阵的定常、多变量、随机线性系统的方法。

In this paper, taking nodal injection power and voltage operation curve of PV node as foundation, according to the basic property of numerical characteristics of random variables and relevant equations for probabilistic load flow calculation the expectations of nodal current, reactive power at PV node and power at balancing node as well as computing formula of covariances are derived by different methods; the computation accuracy of various algorithms are compared and analyzed.

文章以节点注入功率和PV节点电压运行曲线为基础，依据随机变量数字特征的基本性质和概率潮流计算的相关方程，分别采用不同的方法推导了节点电流、PV节点的无功功率及平衡节点功率的均值和协方差计算公式，比较和分析了各种算法的计算精度。

To date, micrometeorology approach based on eddy covariance technique has been regarded as the only direct measurement of material and energy fluxes between atmosphere and biosphere, and has been the key technology of the international flux network.

截止目前，利用微气象学原理的涡度协方差技术是唯一能直接测定生物圈与大气间物质与能量通量的标准方法，成为国际通量观测网络的主要技术。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。