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  2. Covariance and contravariance (computer science) - Wikipedia

    en.wikipedia.org/wiki/Covariance_and_contra...

    An example is the compareTo method: a. compareTo (b) checks whether a comes before or after b in some ordering, but the way to compare, say, two rational numbers will be different from the way to compare two strings. Other common examples of binary methods include equality tests, arithmetic operations, and set operations like subset and union.

  3. Bayesian vector autoregression - Wikipedia

    en.wikipedia.org/wiki/Bayesian_vector_autoregression

    In particular, the Minnesota prior assumes that each variable follows a random walk process, possibly with drift, and therefore consists of a normal prior on a set of parameters with fixed and known covariance matrix, which will be estimated with one of three techniques: Univariate AR, Diagonal VAR, or Full VAR.

  4. Analysis of covariance - Wikipedia

    en.wikipedia.org/wiki/Analysis_of_covariance

    Analysis of covariance (ANCOVA) is a general linear model that blends ANOVA and regression. ANCOVA evaluates whether the means of a dependent variable (DV) are equal across levels of one or more categorical independent variables (IV) and across one or more continuous variables.

  5. Whitening transformation - Wikipedia

    en.wikipedia.org/wiki/Whitening_transformation

    A whitening transformation or sphering transformation is a linear transformation that transforms a vector of random variables with a known covariance matrix into a set of new variables whose covariance is the identity matrix, meaning that they are uncorrelated and each have variance 1. [1]

  6. Covariance function - Wikipedia

    en.wikipedia.org/wiki/Covariance_function

    In probability theory and statistics, the covariance function describes how much two random variables change together (their covariance) with varying spatial or temporal separation. For a random field or stochastic process Z ( x ) on a domain D , a covariance function C ( x , y ) gives the covariance of the values of the random field at the two ...

  7. Taylor expansions for the moments of functions of random ...

    en.wikipedia.org/wiki/Taylor_expansions_for_the...

    To find a second-order approximation for the covariance of functions of two random variables (with the same function applied to both), one can proceed as follows.

  8. Pearson correlation coefficient - Wikipedia

    en.wikipedia.org/wiki/Pearson_correlation...

    Pearson's correlation coefficient is the covariance of the two variables divided by the product of their standard deviations. The form of the definition involves a "product moment", that is, the mean (the first moment about the origin) of the product of the mean-adjusted random variables; hence the modifier product-moment in the name.

  9. Inverse-Wishart distribution - Wikipedia

    en.wikipedia.org/wiki/Inverse-Wishart_distribution

    The result is known in optimal portfolio statistics, as in Theorem 2 Corollary 1 of Bodnar et al, [12] where it is expressed in the inverse form +. As is the case with the Wishart distribution linear transformations of the distribution yield a modified inverse Wishart distribution.