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数据的矩阵描述
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样本 Array of Data
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Descriptive Statistics
Summary numbers to assess the information contained in data Basic descriptive statistics Sample mean Sample variance Sample standard deviation Sample covariance Sample correlation coefficient
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Sample Mean and Sample Variance
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Sample Covariance and Sample Correlation Coefficient
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Standardized Values (or Standardized Scores)
Centered at zero Unit standard deviation Sample correlation coefficient can be regarded as a sample covariance of two standardized variables
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Properties of Sample Correlation Coefficient
Value is between -1 and 1 Magnitude measure the strength of the linear association Sign indicates the direction of the association Value remains unchanged if all xji’s and xjk’s are changed to yji = a xji + b and yjk = c xjk + d, respectively, provided that the constants a and c have the same sign
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Arrays of Basic Descriptive Statistics
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Random Vectors and Random Matrices
Vector whose elements are random variables Random matrix Matrix whose elements are random variables
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Expected Value of a Random Matrix
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Population Mean Vectors
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Covariance
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Statistically Independent
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Population Variance-Covariance Matrices
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Population Correlation Coefficients
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Standard Deviation Matrix
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Correlation Matrix from Covariance Matrix
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Partitioning Covariance Matrix
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Partitioning Covariance Matrix
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Linear Combinations of Random Variables
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Example of Linear Combinations of Random Variables
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Linear Combinations of Random Variables
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Sample Mean Vector and Covariance Matrix
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Partitioning Sample Mean Vector
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Partitioning Sample Covariance Matrix
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Population and Sample 总 体(随机变量或向量)——分布 统计量(随机变量或向量)——分布 数 据 目 标 桥 梁
推 导 统计量(随机变量或向量)——分布 桥 梁 计 算 数 据 出发点
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Random Matrix
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Random Sample Row vectors X1’, X2’, …, Xn’ represent independent observations from a common joint distribution with density function f(x)=f(x1, x2, …, xp) Mathematically, the joint density function of X1’, X2’, …, Xn’ is
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Random Sample Measurements of a single trial, such as Xj’=[Xj1,Xj2,…,Xjp], will usually be correlated The measurements from different trials must be independent The independence of measurements from trial to trial may not hold when the variables are likely to drift over time
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Result 1
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Proof of Result 1
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Proof of Result 1
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Proof of Result 1
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Some Other Estimators
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