caa a22 4500 475793404 CHVBK 20180406123716.0 cr unu---uuuuu 170329e20001201xx s 000 0 eng 10.1007/PL00003981 doi (NATIONALLICENCE)springer-10.1007/PL00003981 Some further remarks on a superiority problem in misspecified restricted singular linear models [Elektronische Daten] [Bao-Xue Zhang, Bai-Sen Liu] Abstract.: Razzaghi (1987) examined the difference of covariance matrices of competing estimators in misspecified restricted linear models. Further, Gross, Trenkler and Liski (1998) extended Razzaghi's result by asserting his sufficient condition for nonnegative definiteness of the covariance matrix difference to be also necessary. In this paper, when the covariance matrix of the disturbance vector is nonnegative definite, the necessary and sufficient conditions for nonnegative definiteness of the covariance matrix difference are derived. So above results are strengthened. Springer-Verlag Berlin Heidelberg, 2000 Key words: Singular linear model nationallicence Restrictions nationallicence Covariance matrix nationallicence Orthogonal projector nationallicence Zhang Bao-Xue Department of Applied Mathematics, Beijing Institute of Technology, China, 100081, CN aut Liu Bai-Sen Department of Mathematics of Tian Jin University, Tian Jin, China, 300072, CN aut https://doi.org/10.1007/PL00003981 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/PL00003981 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Zhang Bao-Xue Department of Applied Mathematics, Beijing Institute of Technology, China, 100081, CN aut NATIONALLICENCE 700 1- Liu Bai-Sen Department of Mathematics of Tian Jin University, Tian Jin, China, 300072, CN aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer