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Download pdf guide - VSN International

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2 Some theory 25We defineU c = D c Uwhere D c is a diagonal matrix whose elements are given by the inverse elementsof the last column of U ie d cii = 1/u ir , i = 1, . . . , r. The matrix U c is thereforeupper triangular with the elements in the last column equal to one. If the vectorσ is ordered in the “natural” way, with σ 2 being the last element, then we candefine the vector of so called “pseudo” stratum variance components byThenceξ = U c σvar (ξ) = D 2 cThe diagonal elements can be manipulated to produce effective stratum degreesof freedom Thompson (1980) vizν i = 2ξ 2 i /d 2 ciiIn this way the closeness to an orthogonal block structure can be assessed.

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