Multi-sample analysis of moment-structures: Asymptotic validity of inferences based on second-order moments

In moment structure analysis with nonnormal data, asymptotic valid inferences require the computation of a consistent (under general distributional assumptions) estimate of the matrix $\Gamma$ of asymptotic variances of sample second--order moments. Such a consistent estimate involves the fourth--order sample moments of the data. In practice, the use of fourth--order moments leads to computational burden and lack of robustness against small samples. In this paper we show that, under certain assumptions, correct asymptotic inferences can be attained when $\Gamma$ is replaced by a matrix $\Omega$ that involves only the second--order moments of the data. The present paper extends to the context of multi--sample analysis of second--order moment structures, results derived in the context of (simple--sample) covariance structure analysis (Satorra and Bentler, 1990). The results apply to a variety of estimation methods and general type of statistics. An example involving a test of equality of means under covariance restrictions illustrates theoretical aspects of the paper.

Scaled and adjusted restricted tests in multi-sample analysis of moment structures

We extend to score, Wald and difference test statistics the scaled and adjusted corrections to goodness-of-fit test statistics developed in Satorra and Bentler (1988a,b). The theory is framed in the general context of multisample analysis of moment structures, under general conditions on the distribution of observable variables. Computational issues, as well as the relation of the scaled and corrected statistics to the asymptotic robust ones, is discussed. A Monte Carlo study illustrates thecomparative performance in finite samples of corrected score test statistics.

Managing competition in professional services and the burden of inertia

Professional services require certain organizational patterns in order to avoid information asymmetries and external effects. These same patterns are used within production structures involving various degrees of monopoly. However, competitive restraints are justified today only when substantial external effects are clearly present, whereas information asymmetries hardly justify such restraints because reputational investments have become widespread in the economy and are relatively efficient in overcoming such asymmetries. As a consequence, innovation in the production of externalities can make competitive constraints unnecessary.

Comparison of information structures

We introduce two ways of comparing information structures, say ${\cal I}$ and${\cal J}$. First we say that ${\cal I}$ is richer than ${\cal J}$ when forevery compact game $G$, all correlated equilibrium distributions of $G$ inducedby ${\cal J}$ are also induced by ${\cal I}$. Second, we say that ${\cal J}$is faithfully reproducable from ${\cal I}$ when all the players can computefrom their information in ${\cal I}$ ``new information'' that they could havereceived from ${\cal J}$. We prove that ${\cal I}$ is richer than ${\cal J}$if and only if ${\cal J}$ is faithfully reproducable from ${\cal I}$.

Wage structures and family economies in the Catalan textile industry in an age of nascent capitalism

This paper deals with changes in managerial practices in Catalonia in anage of nascent capitalism (1830-1925) and adaptive family strategies inorder to face the absence of state welfare. During the 19 t h Century andin the absence of recorded labor contracts, human resources of the firmwere organized by means of implicit contracts and informal labor markets.With the advent of scientific organization of labor, wage per hour workedbegan to be recorded. This is why in the 1920s the perfect competitionmodel applies to our case. On the other hand, in the same period, and inthe absence of state welfare, ideas stemming from cooperative game theoryapply to the pattern of household income formation. Kin related networkswere used to improve the living standards of the household. In thisparticular direction we also show that there was a demonstration effectby means of which migrant s living standards were higher than those ofnatives.

Organizational capital and employment fluctuations

In this paper I present a model in which production requires two types of labor inputs: regular productive tasks and organizational capital, which is accumulated by workers performing organizational tasks. By allocating more workers from organizational to productive tasks, firms can temporarily increase production without hiring. The availability of this intensive margin of labor adjustment, in combination with adjustment costs along the extensive margin (search frictions, firing costs, training costs), makes it optimal to delay employment adjustments. Simulations indicate that this mechanism is quantitatively important even if only a small fraction of workers perform organizational tasks, and explains why the hiring rate is persistent and why employment is slow to recover after the end of a recession.

Endogenous information structures

Many models in the economics literature deal with strategic situations withprivately informed agents. In those models the information structure isassumed to be exogenous and common knowledge. We consider whether suchmodels, and the results they produce, are robust with respect theendogenization of the information structure. The results depend on whetherinformation acquisition is secret or private, and on whether the strategicsituation involves simultaneous or sequential moves. In particular we findthat only when information is secretly acquired and moves are simultaneous,the results are fully robust. When information is acquired secretly butmoves are sequential additional equilibria may appear. Instead, privateinformation acquisition may make the equilibrium set smaller.

Managing by values in the next milenium: Cultural redesign for strategic organizational change

The system of beliefs and values, that shaped the model for management and organizations during the 20th century, is just not good enough today. In order to keep a business functioning well and competing successfully in markets that are increasingly more global, complex, professionally demanding, constantly changing and oriented towards quality and customer satisfaction a new model is needed. In this paper, we will propose that both Management by Instructions (MBI) and Management by Objectives (MBO) today give notoriously inadequate results. By contrast, description of a new approach labeled: Management by Values (MBV), seem to be emerging as a strategic leadership tool. The paper outlines this approach and discusses the implementation of MBV as a tool to redesign culture in organizations and prepare them for the next millenium.

Benchmarking for routines and organizational knowledge

We use best practice benchmarking rationales to propose a dynamic research design that accounts for the endogenous components of across-firms heterogeneous routines to study changes in performance and their link to organizational knowledge investments. We thus contribute to the operationalization of management theoretical frameworks based on resources and routines. The research design employs frontier measures that provide industry-level benchmarking in organizational settings, and proposes some new indicators for firm-level strategic benchmarking. A profit-oriented analysis of the U.S. technology industry during 2000-2011 illustrates the usefulness of our design. Findings reveal that industry revival following economic distress comes along with wider gaps between best and worst performers. Second stage analyses show that increasing intangibles stocks is positively associated with fixed target benchmarking, while enhancing R&D spending is linked to local frontier progress. The discussion develops managerial interpretations of the benchmarking measures that are suitable for control mechanisms and reward systems.

A methodology for the classification of convective structures using meteorological radar: Application to heavy rainfall events on the Mediterranean coast of the Iberian Peninsula

During the period 1996-2000, forty-three heavy rainfall events have been detected in the Internal Basins of Catalonia (Northeastern of Spain). Most of these events caused floods and serious damage. This high number leads to the need for a methodology to classify them, on the basis of their surface rainfall distribution, their internal organization and their physical features. The aim of this paper is to show a methodology to analyze systematically the convective structures responsible of those heavy rainfall events on the basis of the information supplied by the meteorological radar. The proposed methodology is as follows. Firstly, the rainfall intensity and the surface rainfall pattern are analyzed on the basis of the raingauge data. Secondly, the convective structures at the lowest level are identified and characterized by using a 2-D algorithm, and the convective cells are identified by using a 3-D procedure that looks for the reflectivity cores in every radar volume. Thirdly, the convective cells (3-D) are associated with the 2-D structures (convective rainfall areas). This methodology has been applied to the 43 heavy rainfall events using the meteorological radar located near Barcelona and the SAIH automatic raingauge network.

Unipolar transport and shot noise in metal-semiconductor-metal structures

We carry out a self-consistent analytical theory of unipolar current and noise properties of metal-semiconductor-metal structures made of highly resistive semiconductors in the presence of an applied bias of arbitrary strength. By including the effects of the diffusion current we succeed in studying the whole range of carrier injection conditions going from low level injection, where the structure behaves as a linear resistor, to high level injection, where the structure behaves as a space charge limited diode. We show that these structures display shot noise at the highest voltages. Remarkably the crossover from Nyquist noise to shot noise exhibits a complicated behavior with increasing current where an initial square root dependence (double thermal noise) is followed by a cubic power law.

Frequency resolved admittance spectroscopy measurements on In0.52Al0.48As/InxGa1¿xAs/In0.52Al0.48As single quantum well structures

In this work a new admittance spectroscopy technique is proposed to determine the conduction band offset in single quantum well structures (SQW). The proposed technique is based on the study of the capacitance derivative versus the frequency logarithm. This method is found to be less sensitive to parasitic effects, such as leakage current and series resistance, than the classical conductance analysis. Using this technique, we have determined the conduction band offset in In0.52Al0.48As/InxGa1¿xAs/In0.52Al0.48As SQW structures. Two different well compositions, x=0.53, which corresponds to the lattice¿matched case and x=0.60, which corresponds to a strained case, and two well widths (5 and 25 nm) have been considered. The average results are ¿Ec=0.49±0.04 eV for x=0.53 and ¿Ec =0.51±0.04 eV for x=0.6, which are in good agreement with previous reported data.

Strain-induced stabilization of new magnetic spinel structures in epitaxial oxide heterostructures.

We report here on the growth of NiFe2O4 epitaxial thin films of different thickness (3 nm ¿ t ¿ 32 nm) on single crystalline substrates having spinel (MgAl2O4) or perovskite (SrTiO3) structure. Ultrathin films, grown on any of those substrates, display a huge enhancement of the saturation magnetization: we will show that partial cationic inversion may account for this enhancement, although we will argue that suppression of antiparallel collinear spin alignment due to size-effects cannot be excluded. Besides, for thicker films, the magnetization of films on MAO is found to be similar to that of bulk ferrite; in contrast, the magnetization of films on STO is substantially lower than bulk. We discuss on the possible mechanisms leading to this remarkable difference of magnetization.

Micro-Raman study of stress distribution in local isolation structures and correlation with transmission electron microscopy

Stress in local isolation structures is studied by micro‐Raman spectroscopy. The results are correlated with predictions of an analytical model for the stress distribution and with cross‐sectional transmission electron microscopy observations. The measurements are performed on structures on which the Si3N4 oxidation mask is still present. The influence of the pitch of the periodic local isolation pattern, consisting of parallel lines, the thickness of the mask, and the length of the bird"s beak on the stress distribution are studied. It is found that compressive stress is present in the Si substrate under the center of the oxidation mask lines, with a magnitude dependent on the width of the lines. Large tensile stress is concentrated under the bird"s beak and is found to increase with decreasing length of the bird"s beak and with increasing thickness of the Si3N4 film.

Raman scattering and photoluminescence analysis of silicon on insulator structures obtained by single and multiple oxygen implants

An analysis of silicon on insulator structures obtained by single and multiple implants by means of Raman scattering and photoluminescence spectroscopy is reported. The Raman spectra obtained with different excitation powers and wavelengths indicate the presence of a tensile strain in the top silicon layer of the structures. The comparison between the spectra measured in both kinds of samples points out the existence in the multiple implant material of a lower strain for a penetration depth about 300 nm and a higher strain for higher penetration depths. These results have been correlated with transmission electron microscopy observations, which have allowed to associate the higher strain to the presence of SiO2 precipitates in the top silicon layer, close to the buried oxide. The found lower strain is in agreement with the better quality expected for this material, which is corroborated by the photoluminescence data.