Search results for "Parametric"
showing 10 items of 980 documents
Sealing ability of five different retrograde filling materials.
1996
The sealing ability of Amalgam, Harvard-Cement, Diaket, gold-leaf, and Ketac-Endo as retrofilling materials was investigated. Paper cones were fixed with Harvard-Cement in the instrumented roots of 100 extracted human incisors. Apicectomy was performed and a 2-mm-deep retrograde cavity was prepared. Teeth were assigned to five groups (n = 20); each group received a different filling material. Surfaces of the roots were isolated with nail polish. Teeth, were stored in 1% methylene blue dye for 72 h. Roots were sectioned, and the depth of dye penetration was evaluated through a stereomicroscope. Retrofills with Ketac-Endo showed significantly less leakage compared with amalgam. There was no s…
Feasibility of Linear Parametric Estimation of Dynamic Information Measures to assess Physiological Stress from Short-Term Cardiovascular Variability
2021
Extensive efforts have been recently devoted to implement fast and reliable algorithms capable of assessing the physiological response of the organism to physiological stress. In this study, we propose the comparison between model-free and linear parametric methods as regards their ability to detect alterations in the dynamics and in the complexity of cardiovascular and respiratory variability evoked by postural and mental stress. Dynamic entropy (DE) and information storage (IS) measures were calculated on three physiological time-series, i.e. heart period, respiratory volume and systolic arterial pressure, on 61 healthy subjects monitored in resting conditions as well as during head-up ti…
Nonlinear System Response for Impulsive Parametric Input
1997
In engineering applications when the intensity of external forces depends on the response of the system, the input is called parametric. In this paper dynamical systems subjected to a parametric deterministic impulse are dealt with. Particular attention has been devoted to the evaluation of the discontinuity of the response when the parametric impulse occurs. The usual forward difference and trapezoidal integration schemes have been shown to provide only approximated solutions of the jump of the response; hence, the exact solution has been pursued and presented under the form of a numerical series. The impulse is represented throughout the paper by means of a classical Dirac’s delta functio…
A multicriteria extension of the efficient market hypothesis
2021
Challenging the Efficient Market Hypothesis (EMH) has been a recurrent topic for researchers and practitioners since its formulation. Hundreds of empirical studies claim to either prove or disprove the EMH by means of a number of heterogeneous methods. Even though the EMH is usually adjusted to a measure of risk, there is a lack of a formal analysis within a multiple-criteria context. In this paper, we propose a extension of the EMH that accommodates the foundations of multiple-criteria decision analysis. To this end, we rely on a family of parametric signed dissimilarity measures to assess multidimensional performance differences. Since normalization is a critical step in our approach to a…
Decomposing changes in the conditional variance of GDP over time
2017
A well established fact in the growth empirics literature is the increasing (unconditional) variation in output per capita across countries. We propose a nonparametric decomposition of the conditional variation of output per capita across countries to capture different channels over which the variation might be increasing. We find that OECD countries have experienced diminishing conditional variation while other regions have experienced increasing conditional variation. Our decomposition suggests that most of these changes in the conditional variance of output are due to unobserved factors not accounted for by the traditional growth determinants. In addition to this we show that these facto…
How efficient is maize production among smallholder farmers in Zimbabwe? A comparison of semiparametric and parametric frontier efficiency analyses
2018
The controversial Fast Track Land Reform Programme in Zimbabwe that redistributes commercially-owned farmland to smallholder households has caused concerns about the efficiency of agricultural prod...
Residual-based block bootstrap for cointegration testing
2010
We propose a new testing procedure to determine the rank of cointegration. This new method is based on the nonparametric resampling procedure, so-called Residual-Based Block Bootstrap (RBB), which is developed by Paparoditis and Politis (2003) in the context of unit root testing. Through Monte Carlo experiments we show that, in small samples, the RBB cointegration test has good power properties in relation to the other two well-known tests for cointegration, such as the Augmented Dickey–Fuller (ADF), applied to the residual of a cointegrating regression, and the Johansen's maximum eigenvalue tests. Likewise, this article looks at the influence played by the correlation of the ‘X’ variables …
Productivity Polarization and Sectoral Dynamics in European Regions
2007
Abstract We show that the distribution dynamics of productivity in European regions displays polarization with a nonlinear growth path. We investigate the factors explaining this behavior focusing in particular on sectoral composition. The β -convegence analysis reveals that initial shares of Manufacturing and Other Market Services have a nonlinear impact on growth, while spatial effects are not statistically significant. By decomposing the dynamics of aggregate productivity in terms of sectoral dynamics, we show that productivity in Manufacturing, Non Market Services, and Other Market Services does not converge, for the complex interaction of technological spillovers and specialization eff…
Directional distance functions and environmental regulation
2005
Abstract In this paper we use directional technology distance functions to evaluate the impact of environmental regulations on firms’ performance. Following Fare et al. [Fare, R., Grosskopf, S., Lovell, C.A.K., Pasurka, C., 1989. Multilateral productivity comparisons when some outputs are undesirable: a nonparametric approach. The Review of Economics and Statistics 71, 90–98.], we construct an index that measures opportunity costs for individual firms arising from regulations that prevent free disposal of wastes. The methodology is applied to a sample of Spanish producers of ceramic pavements. We assume that firms maximise desirable output simultaneously reducing inputs, with no change in t…
Estimating Engel curves under unit and item nonresponse
2010
SUMMARY This paper estimates food Engel curves using data from the first wave of the Survey on Health, Aging and Retirement in Europe (SHARE). Our statistical model simultaneously takes into account selectivity due to unit and item nonresponse, endogeneity problems, and issues related to flexible specification of the relationship of interest. We estimate both parametric and semiparametric specifications of the model. The parametric specification assumes that the unobservables in the model follow a multivariate Gaussian distribution, while the semiparametric specification avoids distributional assumptions about the unobservables. Copyright © 2011 John Wiley & Sons, Ltd.