This paper extends, in an asymptotic sense, the strong and the weaker mean square error criteria and corresponding tests to linear models with non-spherical disturbances where the error covariance matrix is unknown but a consistent estimator for it is available. The mean square error tests of Toro-Vizcorrondo and Wallace (1968) and Wallace (1972) test for the superiority of restricted over unre...

In this paper we survey methods to control for regression model error that is correlated within groups or clusters, but is uncorrelated across groups or clusters. Then failure to control for the clustering can lead to understatement of standard errors and overstatement of statistical signi cance, as emphasized most notably in empirical studies by Moulton (1990) and Bertrand, Du o and Mullainath...

The revised Japanese clinical guidelines for myasthenia gravis (MG) and Lambert–Eaton myasthenic syndrome (LEMS) were published in 2022. notable points these (GLs) are as follows: (i) the first GLs to include a description of LEMS; (ii) diagnostic criteria MG lessen incidence false negative patients; (iii) is divided into six subtypes; (iv) high-dose oral steroid regimen with escalation de-esca...

Quantile regression (QR) is becoming increasingly popular due to its relevance in many scientific investigations. Linear and nonlinear QR models have been studied extensively, while recent research focuses on the single index quantile regression (SIQR) model. Compared to the single index mean regression problem, the fitting and the asymptotic theory of the SIQR model are more complicated due to...

This paper gives componentwise perturbation analyses for Q and R in the QR factorization A = QR, QTQ = I , R upper triangular, for a given realm×nmatrixA of rank n. Such specific analyses are important for examplewhen the columns ofA are badly scaled. First order perturbation bounds are given for both Q and R. The analyses more accurately reflect the sensitivity of the problem than previous suc...

We study two linear estimators for stationary invertible VARMA models in echelon form (for identification), with known Kronecker indices. Such linear estimators are much simpler to compute than Gaussian maximum likelihood (ML) estimators often proposed for such models, which are highly nonlinear. The first estimator is an improved two-step estimator which can be interpreted as a generalized lea...

BACKGROUND In transcatheter aortic valve replacement (TAVR) the trans-apical approach (TA) is associated with apical myocardial injury but it is unknown if this injury impacts myocardial function. This study was performed to assess the impact of TA on apical longitudinal strain (ALS) and global longitudinal strain (GLS) after TAVR. METHODS 44 consecutive patients (age 81 ± 7 years, 48% male) ...