In dynamic regression models conditional maximum likelihood (least-squares) coeffi cient and variance estimators are biased. From expansions of the coeffi cient variance and its estimator we obtain an approximation to the bias in variance estimation and a bias corrected variance estimator, for both the standard and a bias corrected coeffi cient estimator. These enable a comparison of their mean...

Background: Strength, muscular endurance, and fl exibility are important components of healthy back function. This study determined the reliability and evaluated the validity of selected low back fi eld tests (FITNESSGRAM® Trunk Extension [FG-TE] and Box 90° Dynamic Trunk Extension [B-90° DTE]) when compared to laboratory tests (Parallel Roman Chair Dynamic Trunk Extension [PRC-DTE], Parallel R...

Snow scavenging of sub-micrometre aerosol particles is poorly known, even though it is an important aerosol removal mechanism in the polar and mountainous regions as well as in the upper troposphere and in mid-latitudes in winter. In our study, snow scavenging coeffi cients were calculated using four years of particle number concentration spectra measurements together with meteorological measur...

Introduction: Prediction of mesiodistal (MD) width of unerupted permanent canines and premolars is an essential aspect of mixed dentition analysis. Several methods are used to predict tooth width. The best methods demonstrate high values of correlation and determination coeffi cients. In this study, we aimed to determine the linear regression equation that would predict the sum of the MD widths...

When there is exact collinearity between regressors, their individual coeffi cients are not identified, but given an informative prior their Bayesian posterior means are well defined. The case of high but not exact collinearity is more complicated but similar results follow. Just as exact collinearity causes non-identification of the parameters, high collinearity can be viewed as weak identific...

The work of Zhang et al. [18] investigates the existence of periodic solutions in a ODE model, of a three species food chain, based on a modified Leslie-Gower scheme. They consider time dependent periodic coeffi cients to model periodicity of the natural environment. Their main result is that under certain restrictions on these coeffi cients, there exists at least one periodic solution to the t...

This paper proposes a variant of the classical HAUSMAN specifi cation test commonly employed to decide whether the estimation of a random-eff ects model is a viable alternative to estimating fi xed eff ects. Whereas the classical test probes the equality of fi xedand random eff ects, the proposed variant focuses on the equality of between-groups and fi xed-eff ects coeffi cients. While both tes...

Noodle cooking quality is an important aspect in assessing processing quality of Chinese fresh noodles. Forty-six Chinese wheat cultivars and advanced lines from the Northern Plain and the Yellow and Huai River Valleys Winter Wheat Regions were used to determine the relationship between wheat quality characters and evaluation parameters of Chinese fresh noodle cooking quality, including total o...

L. Blacha, Silesian University of Technology, Faculty of Materials Engineering and Metallurgy, Katowice J. Mizera, Warsaw University of Technology, Faculty of Materials Engineering, Warszawa P. Folęga, Silesian University of Technology, Faculty of Transport, Katowice, Poland In the present paper, the rate of aluminium evaporation from the Ti-6Al-7Nb alloy during smelting with the use of VIM met...

This paper proposes a variant of the classical HAUSMAN specifi cation test commonly employed to decide whether the estimation of a random-eff ects model is a viable alternative to estimating fi xed eff ects. Whereas the classical test probes the equality of fi xedand random eff ects, the proposed variant focuses on the equality of between-groups and fi xed-eff ects coeffi cients. While both tes...