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Generalized linear array model

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In statistics, the generalized linear array model (GLAM) is used for analyzing data sets with array structures. It based on the generalized linear model with the design matrix written as a Kronecker product.

Overview

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The generalized linear array model or GLAM was introduced in 2006.[1] Such models provide a structure and a computational procedure for fitting generalized linear models or GLMs whose model matrix can be written as a Kronecker product and whose data can be written as an array. In a large GLM, the GLAM approach gives very substantial savings in both storage and computational time over the usual GLM algorithm.

Suppose that the data ๐˜ is arranged in a d-dimensional array with size n1ร—n2ร—โ‹ฏร—nd; thus, the corresponding data vector ๐ฒ=vecโก(๐˜) has size n1n2n3โ‹ฏnd. Suppose also that the design matrix is of the form

๐—=๐—dโŠ—๐—dโˆ’1โŠ—โ‹ฏโŠ—๐—1.

The standard analysis of a GLM with data vector ๐ฒ and design matrix ๐— proceeds by repeated evaluation of the scoring algorithm

๐—โ€ฒ๐–~ฮด๐—๐œฝฬ‚=๐—โ€ฒ๐–~ฮด๐œฝ~,

where ๐œฝ~ represents the approximate solution of ๐œฝ, and ๐œฝฬ‚ is the improved value of it; ๐–ฮด is the diagonal weight matrix with elements

wiiโˆ’1=(โˆ‚ฮทiโˆ‚ฮผi)2var(yi),

and

๐ณ=๐œผ+๐–ฮดโˆ’1(๐ฒโˆ’๐)

is the working variable.

Computationally, GLAM provides array algorithms to calculate the linear predictor,

๐œผ=๐—๐œฝ

and the weighted inner product

๐—โ€ฒ๐–~ฮด๐—

without evaluation of the model matrix ๐—.

Example

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In 2 dimensions, let ๐—=๐—2โŠ—๐—1, then the linear predictor is written ๐—1๐œฃ๐—2โ€ฒ where ๐œฃ is the matrix of coefficients; the weighted inner product is obtained from G(๐—1)โ€ฒ๐–G(๐—2) and ๐– is the matrix of weights; here G(๐Œ) is the row tensor function of the rร—c matrix ๐Œ given by[1]

G(๐Œ)=(๐ŒโŠ—๐Ÿโ€ฒ)โˆ˜(๐Ÿโ€ฒโŠ—๐Œ)

where โˆ˜ means element by element multiplication and ๐Ÿ is a vector of 1's of length c.

On the other hand, the row tensor function G(๐Œ) of the rร—c matrix ๐Œ is the example of Face-splitting product of matrices, which was proposed by Vadym Slyusar in 1996:[2][3][4][5]

๐Œโˆ™๐Œ=(๐ŒโŠ—๐Ÿ๐–ณ)โˆ˜(๐Ÿ๐–ณโŠ—๐Œ),

where โˆ™ means Face-splitting product.

These low storage high speed formulae extend to d-dimensions.

Applications

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GLAM is designed to be used in d-dimensional smoothing problems where the data are arranged in an array and the smoothing matrix is constructed as a Kronecker product of d one-dimensional smoothing matrices.

References

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  1. 1 2 Currie, I. D.; Durban, M.; Eilers, P. H. C. (2006). "Generalized linear array models with applications to multidimensional smoothing". Journal of the Royal Statistical Society. 68 (2): 259โ€“280. doi:10.1111/j.1467-9868.2006.00543.x. S2CIDย 10261944.
  2. โ†‘ Slyusar, V. I. (December 27, 1996). "End products in matrices in radar applications" (PDF). Radioelectronics and Communications Systems. 41 (3): 50โ€“53.
  3. โ†‘ Slyusar, V. I. (1997-05-20). "Analytical model of the digital antenna array on a basis of face-splitting matrix products" (PDF). Proc. ICATT-97, Kyiv: 108โ€“109.
  4. โ†‘ Slyusar, V. I. (1997-09-15). "New operations of matrices product for applications of radars" (PDF). Proc. Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED-97), Lviv.: 73โ€“74.
  5. โ†‘ Slyusar, V. I. (March 13, 1998). "A Family of Face Products of Matrices and its Properties" (PDF). Cybernetics and Systems Analysis C/C of Kibernetika I Sistemnyi Analiz. 1999. 35 (3): 379โ€“384. doi:10.1007/BF02733426. S2CIDย 119661450.