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WALS (version 0.2.5)

svdLSplus: Internal function: Uses SVD components to compute final estimate via Sherman-Morrison-Woodbury formula.

Description

Solves the equation system in walsNB via Sherman-Morrison-Woodbury formula for the unrestricted estimator \(\hat{\gamma}_{u}\).

Usage

svdLSplus(U, V, singularVals, y, ell, geB)

Arguments

U

Left singular vectors of \(\bar{Z}\) or \(\bar{Z}_{1}\) from svd.

V

Right singular vectors of \(\bar{Z}\) or \(\bar{Z}_{1}\) from svd.

singularVals

Singular values of \(\bar{Z}\) or \(\bar{Z}_{1}\) from svd.

y

"Pseudo"-response, see details.

ell

Vector \(\bar{\ell}\) from section "Simplification for computing \(\tilde{\gamma}_{u}\)" huynhwals;textualWALS

geB

Scalar \(\bar{g} \bar{\epsilon} / (1 + B)\). See section "Simplification for computing \(\tilde{\gamma}_{u}\)" huynhwals;textualWALS for definition of \(\bar{g}\), \(\bar{\epsilon}\) and \(B\).

Details

The function can be reused for the computation of the fully restricted estimator \(\tilde{\gamma}_{1r}\) and the model averaged estimator \(\hat{\gamma}_{1}\).

For \(\tilde{\gamma}_{1r}\) and \(\hat{\gamma}_{1}\) use U, V and singularVals from SVD of \(\bar{Z}_{1}\).

For \(\hat{\gamma}_{u}\) and \(\tilde{\gamma}_{1r}\) use same pseudo-response \(\bar{y_{0}} - \bar{t} \bar{\epsilon} \bar{\Psi}^{-1/2} \bar{q}\) in argument y.

For \(\hat{\gamma}_{1}\) use pseudo-response \(\bar{y_{0}} - \bar{t} \bar{\epsilon} \bar{\Psi}^{-1/2} \bar{q} - (\bar{Z}_{2} + \bar{g} \bar{\epsilon} \bar{\Psi}^{-1/2} \bar{q} \bar{q}^{\top} Z_{2}) \hat{\gamma}_{2}\).

See section "Note on function svdLSplus from WALS" in huynhwals;textualWALS.

References