Measure of covariance of components of a random vector
Part of a series on Statistics
Correlation and covariance
For random vectors
Autocorrelation matrix
Cross-correlation matrix
Auto-covariance matrix
Cross-covariance matrix
For stochastic processes
Autocorrelation function
Cross-correlation function
Autocovariance function
Cross-covariance function
For deterministic signals
Autocorrelation function
Cross-correlation function
Autocovariance function
Cross-covariance function
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Not to be confused with Cross-covariance matrix.
In probability theory and statistics, a covariance matrix (also known as auto-covariance matrix, dispersion matrix, variance matrix, or variance–covariance matrix) is a square matrix giving the covariance between each pair of elements of a given random vector.
Intuitively, the covariance matrix generalizes the notion of variance to multiple dimensions. As an example, the variation in a collection of random points in two-dimensional space cannot be characterized fully by a single number, nor would the variances in the and directions contain all of the necessary information; a matrix would be necessary to fully characterize the two-dimensional variation.
Any covariance matrix is symmetric and positive semi-definite and its main diagonal contains variances (i.e., the covariance of each element with itself).
The covariance matrix of a random vector is typically denoted by , or .
a covariancematrix (also known as auto-covariancematrix, dispersion matrix, variance matrix, or variance–covariancematrix) is a square matrix giving...
calculating covariance Analysis of covariance Autocovariance Covariance function CovariancematrixCovariance operator Distance covariance, or Brownian...
variance-covariancematrix (or simply covariancematrix) showing also the relationship between each pair of variables. This would be a 3×3 matrix when 3...
statistics, sometimes the covariancematrix of a multivariate random variable is not known but has to be estimated. Estimation of covariance matrices then deals...
variable. Then the variances and covariances can be placed in a covariancematrix, in which the (i, j) element is the covariance between the i th random variable...
{\displaystyle 1\leq j\leq k} . The inverse of the covariancematrix is called the precision matrix, denoted by Q = Σ − 1 {\displaystyle {\boldsymbol {Q}}={\boldsymbol...
of the data's covariancematrix. Thus, the principal components are often computed by eigendecomposition of the data covariancematrix or singular value...
_{k}} is the covariancematrix of the observation noise, v k {\displaystyle \mathbf {v} _{k}} . Additionally, the cross covariancematrix is also needed...
(e_{t}e_{t}')=\Omega \,} . The contemporaneous covariancematrix of error terms is a k × k positive-semidefinite matrix denoted Ω. E ( e t e t − k ′ ) = 0 {\displaystyle...
positive semi-definite square matrix, commonly referred to as the variance-covariancematrix (or simply as the covariancematrix). If X {\displaystyle X} is...
generalized least squares, when all the off-diagonal entries of the covariancematrix of the errors, are null. The fit of a model to a data point is measured...
referred to as the residual maker matrix or the annihilator matrix. The covariancematrix of the residuals r {\displaystyle \mathbf {r} } , by error propagation...
( ℜ ( Z ) , ℑ ( Z ) ) {\displaystyle (\Re {(Z)},\Im {(Z)})} has a covariancematrix of the form: [ Var [ ℜ ( Z ) ] Cov [ ℑ ( Z ) , ℜ ( Z ) ] Cov ...
steps: a translation, the computation of a covariancematrix, and the computation of the optimal rotation matrix. Both sets of coordinates must be translated...
The covariancematrix (also called second central moment) K Z Z {\displaystyle \operatorname {K} _{\mathbf {Z} \mathbf {Z} }} contains the covariances between...
the value of x {\displaystyle x} . More generally, if the variance-covariancematrix of disturbance ε i {\displaystyle \varepsilon _{i}} across i {\displaystyle...
of random variables with a known covariancematrix into a set of new variables whose covariance is the identity matrix, meaning that they are uncorrelated...
Pentland in face classification. The eigenvectors are derived from the covariancematrix of the probability distribution over the high-dimensional vector space...
respective random variables.: p.333 The covariancematrix (also called second central moment or variance-covariancematrix) of an n × 1 {\displaystyle n\times...
three parameters: location parameter μ, covariancematrix Γ {\displaystyle \Gamma } , and the relation matrix C {\displaystyle C} . The standard complex...
a stochastic process, the autocovariance is a function that gives the covariance of the process with itself at pairs of time points. Autocovariance is...
conjugate prior of the inverse covariance-matrix of a multivariate-normal random-vector. Suppose G is a p × n matrix, each column of which is independently...
covariancematrix of the samples. When the affine span of the samples is not the entire R N {\displaystyle \mathbb {R} ^{N}} , the covariancematrix would...
matrix. In multivariate statistics and probability theory, the scatter matrix is a statistic that is used to make estimates of the covariancematrix,...
column vector μ {\displaystyle \mu } , and their variances and covariances in a covariancematrix Σ {\displaystyle \Sigma } . Consider a portfolio of risky...