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Asymptotic normality and consistency of a two-stage generalized least squares estimator in the growth curve model

Abstract

Let Y=X\boldsΘZ+\boldsE\mathbf{Y}=\mathbf{X}\bolds{\Theta}\mathbf{Z}'+\bolds{\mathcal {E}} be the growth curve model with \boldsE\bolds{\mathcal{E}} distributed with mean 0\mathbf{0} and covariance In\boldsΣ\mathbf{I}_n\otimes\bolds{\Sigma}, where \boldsΘ\bolds{\Theta}, \boldsΣ\bolds{\Sigma} are unknown matrices of parameters and X\mathbf{X}, Z\mathbf{Z} are known matrices. For the estimable parametric transformation of the form \boldsγ=C\boldsΘD\bolds {\gamma}=\mathbf{C}\bolds{\Theta}\mathbf{D}' with given C\mathbf{C} and D\mathbf{D}, the two-stage generalized least-squares estimator \boldsγ^(Y)\hat{\bolds \gamma}(\mathbf{Y}) defined in (7) converges in probability to \boldsγ\bolds\gamma as the sample size nn tends to infinity and, further, n[\boldsγ^(Y)\boldsγ]\sqrt{n}[\hat{\bolds{\gamma}}(\mathbf{Y})-\bolds {\gamma}] converges in distribution to the multivariate normal distribution \mathcalN(0,(CR1C)(\mathbfD(Z\boldsΣ1Z)1D))\ma thcal{N}(\mathbf{0},(\mathbf{C}\mathbf{R}^{-1}\mathbf{C}')\otimes(\mat hbf{D}(\mathbf{Z}'\bolds{\Sigma}^{-1}\mathbf{Z})^{-1}\mathbf{D}')) under the condition that limnXX/n=R\lim_{n\to\infty}\mathbf{X}'\mathbf{X}/n=\mathbf{R} for some positive definite matrix R\mathbf{R}. Moreover, the unbiased and invariant quadratic estimator \boldsΣ^(Y)\hat{\bolds{\Sigma}}(\mathbf{Y}) defined in (6) is also proved to be consistent with the second-order parameter matrix \boldsΣ\bolds{\Sigma}.

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