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  2. Contrast (statistics) - Wikipedia

    en.wikipedia.org/wiki/Contrast_(statistics)

    A contrast is defined as the sum of each group mean multiplied by a coefficient for each group (i.e., a signed number, c j). [10] In equation form, = ¯ + ¯ + + ¯ ¯, where L is the weighted sum of group means, the c j coefficients represent the assigned weights of the means (these must sum to 0 for orthogonal contrasts), and ¯ j represents the group means. [8]

  3. Orthogonal polynomials - Wikipedia

    en.wikipedia.org/wiki/Orthogonal_polynomials

    It induces a notion of orthogonality in the usual way, namely that two polynomials are orthogonal if their inner product is zero. Then the sequence ( P n ) ∞ n =0 of orthogonal polynomials is defined by the relations deg ⁡ P n = n , P m , P n = 0 for m ≠ n . {\displaystyle \deg P_{n}=n~,\quad \langle P_{m},\,P_{n}\rangle =0\quad {\text ...

  4. Orthogonality principle - Wikipedia

    en.wikipedia.org/wiki/Orthogonality_principle

    In the special case of linear estimators described above, the space is the set of all functions of and , while is the set of linear estimators, i.e., linear functions of only. Other settings which can be formulated in this way include the subspace of causal linear filters and the subspace of all (possibly nonlinear) estimators.

  5. Response surface methodology - Wikipedia

    en.wikipedia.org/wiki/Response_surface_methodology

    Orthogonality The property that allows individual effects of the k-factors to be estimated independently without (or with minimal) confounding. Also orthogonality provides minimum variance estimates of the model coefficient so that they are uncorrelated. Rotatability The property of rotating points of the design about the center of the factor ...

  6. Uncorrelatedness (probability theory) - Wikipedia

    en.wikipedia.org/wiki/Uncorrelatedness...

    In general, uncorrelatedness is not the same as orthogonality, except in the special case where at least one of the two random variables has an expected value of 0. In this case, the covariance is the expectation of the product, and X {\displaystyle X} and Y {\displaystyle Y} are uncorrelated if and only if E ⁡ [ X Y ] = 0 {\displaystyle ...

  7. Pearson correlation coefficient - Wikipedia

    en.wikipedia.org/.../Pearson_correlation_coefficient

    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.

  8. Legendre polynomials - Wikipedia

    en.wikipedia.org/wiki/Legendre_polynomials

    The Legendre polynomials were first introduced in 1782 by Adrien-Marie Legendre [3] as the coefficients in the expansion of the Newtonian potential | ′ | = + ′ ′ ⁡ = = ′ + (⁡), where r and r′ are the lengths of the vectors x and x′ respectively and γ is the angle between those two vectors.

  9. Orthonormality - Wikipedia

    en.wikipedia.org/wiki/Orthonormality

    A unit vector means that the vector has a length of 1, which is also known as normalized. Orthogonal means that the vectors are all perpendicular to each other. A set of vectors form an orthonormal set if all vectors in the set are mutually orthogonal and all of unit length. An orthonormal set which forms a basis is called an orthonormal basis.