895 resultados para multilevel confirmatory factor analysis


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This dissertation develops a strategic management accounting perspective of inventory routing. The thesis studies the drivers of cost efficiency gains by identifying the role of the underlying cost structure, demand, information sharing, forecasting accuracy, service levels, vehicle fleet, planning horizon and other strategic factors as well as the interaction effects among these factors with respect to performance outcomes. The task is to enhance the knowledge of the strategic situations that favor the implementation of inventory routing systems, understanding cause-and-effect relationships, linkages and gaining a holistic view of the value proposition of inventory routing. The thesis applies an exploratory case study design, which is based on normative quantitative empirical research using optimization, simulation and factor analysis. Data and results are drawn from a real world application to cash supply chains. The first research paper shows that performance gains require a common cost component and cannot be explained by simple linear or affine cost structures. Inventory management and distribution decisions become separable in the absence of a set-dependent cost structure, and neither economies of scope nor coordination problems are present in this case. The second research paper analyzes whether information sharing improves the overall forecasting accuracy. Analysis suggests that the potential for information sharing is limited to coordination of replenishments and that central information do not yield more accurate forecasts based on joint forecasting. The third research paper develops a novel formulation of the stochastic inventory routing model that accounts for minimal service levels and forecasting accuracy. The developed model allows studying the interaction of minimal service levels and forecasting accuracy with the underlying cost structure in inventory routing. Interestingly, results show that the factors minimal service level and forecasting accuracy are not statistically significant, and subsequently not relevant for the strategic decision problem to introduce inventory routing, or in other words, to effectively internalize inventory management and distribution decisions at the supplier. Consequently the main contribution of this thesis is the result that cost benefits of inventory routing are derived from the joint decision model that accounts for the underlying set-dependent cost structure rather than the level of information sharing. This result suggests that the value of information sharing of demand and inventory data is likely to be overstated in prior literature. In other words, cost benefits of inventory routing are primarily determined by the cost structure (i.e. level of fixed costs and transportation costs) rather than the level of information sharing, joint forecasting, forecasting accuracy or service levels.

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The methods of secondary wood processing are assumed to evolve over time and to affect the requirements set for the wood material and its suppliers. The study aimed at analysing the industrial operating modes applied by joinery and furniture manufacturers as sawnwood users. Industrial operating mode was defined as a pattern of important decisions and actions taken by a company which describes the company's level of adjustment in the late-industrial transition. A non-probabilistic sample of 127 companies was interviewed, including companies from Denmark, Germany, the Netherlands, and Finland. Fifty-two of the firms were furniture manufacturers and the other 75 were producing windows and doors. Variables related to business philosophy, production operations, and supplier choice criteria were measured and used as a basis for a customer typology; variables related to wood usage and perceived sawmill performance were measured to be used to profile the customer types. Factor analysis was used to determine the latent dimensions of industrial operating mode. Canonical correlations analysis was applied in developing the final base for classifying the observations. Non-hierarchical cluster analysis was employed to build a five-group typology of secondary wood processing firms; these ranged from traditional mass producers to late-industrial flexible manufacturers. There is a clear connection between the amount of late-industrial elements in a company and the share of special and customised sawnwood it uses. Those joinery or furniture manufacturers that are more late-industrial also are likely to use more component-type wood material and to appreciate customer-oriented technical precision. The results show that the change is towards the use of late-industrial sawnwood materials and late-industrial supplier relationships.

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According to the literature and statistical figures, professional drivers constitute a high-risk group in traffic and should be investigated in connection with the factors related to safe driving. However, safety-related behaviours and outcomes among professional drivers have attracted very little attention from safety researchers. In addition, comparing different professional and non-professional driver groups in terms of critical on-the-road characteristics and outcomes has been indicated in the literature as being necessary for a more comprehensive understanding of driver groups and the nature of driving itself. The aim of the present study was to investigate professional driving from a safety climate stand point in relation to predominant driving-related factors and by considering the differences between driver groups. Hence, four Sub-studies were conducted according to a framework emphasizing the relationships between safety climate, driver groups, driver stress, human factors (i.e., driver behaviour and performance) and accidents. Demographic information, as well as data for driver behaviour, performance, and driver stress was collected by questionnaire. The data was analysed using factor analysis, analysis of covariance as well as hierarchical and logistic regression analysis. The results revealed multi-dimensional factor structures for the safety climate measures. Considering the relationships between variables, differences were evidenced regarding on-the-road stress reactions, risky driver behaviours and penalties, between the various professional and non-professional driver groups. Driver stress was found to be related to accidents. The results also indicated that the safety climate has positive relationships with both driver behaviour and performance, and as well as involvement in accidents. The present study has a number of critical implications resulting from the fact that the way in which the effects of safety climate on professional driving were investigated, as well as the differences between professional and non-professional driver groups, was unique. Additionally, for the first time, a safety climate scale was developed specifically for professional drivers. According to the results of the study and to previous literature, a tentative model was proposed representing a possible route for the relationships between safety climate, human factors, driver stress, driver groups and accidents, by emphasizing the effects of safety climate.

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The purpose of this study was to find out whether food-related lifestyle guides and explains product evaluations, specifically, consumer perceptions and choice evaluations of five different food product categories: lettuce, mincemeat, savoury sauce, goat cheese, and pudding. The opinions of consumers who shop in neighbourhood stores were considered most valuable. This study applies means-end chain (MEC) theory, according to which products are seen as means by which consumers attain meaningful goals. The food-related lifestyle (FRL) instrument was created to study lifestyles that reflect these goals. Further, this research has adopted the view that the FRL functions as a script which guides consumer behaviour. Two research methods were used in this study. The first was the laddering interview, the primary aim of which was to gather information for formulating the questionnaire of the main study. The survey consisted of two separate questionnaires. The first was the FRL questionnaire modified for this study. The aim of the other questionnaire was to determine the choice criteria for buying five different categories of food products. Before these analyses could be made, several data modifications were made following MEC analysis procedures. Beside forming FRL dimensions by counting sum-scores from the FRL statements, factor analysis was run in order to elicit latent factors underlying the dimensions. The lifestyle factors found were adventurous, conscientious, enthusiastic, snacking, moderate, and uninvolved lifestyles. The association analyses were done separately for each choice of product as well as for each attribute-consequence linkage with a non-parametric Mann-Whitney U test. The testing variables were FRL dimensions and the FRL lifestyle factors. In addition, the relation between the attribute-consequence linkages and the demographic variables were analysed. Results from this study showed that the choice of product is sequential, so that consumers first categorize products into groups based on specific criteria like health or convenience. It was attested that the food-related lifestyles function as a script in food choice and that the FRL instrument can be used to predict consumer buying behaviour. Certain lifestyles were associated with the choice of each product category. The actual product choice within a product category then appeared to be a different matter. In addition, this study proposes a modification to the FRL instrument. The positive towards advertising FRL dimension was modified to examine many kinds of information search including the internet, TV, magazines, and other people. This new dimension, which was designated as being open to additional information, proved to be very robust and reliable in finding differences in consumer choice behaviour. Active additional information search was linked to adventurous and snacking food-related lifestyles. The results of this study support the previous knowledge that consumers expect to get many benefits simultaneously when they buy food products. This study brought detailed information about the benefits sought, the combination of benefits differing between products and between respondents. Household economy, pleasure and quality were emphasized with the choice of lettuce. Quality was the most significant benefit in choosing mincemeat, but health related benefits were often evaluated as well. The dominant benefits linked to savoury sauce were household economic benefits, expected pleasurable experiences, and a lift in self-respect. The choice of goat cheese appeared not to be an economic decision, self-respect, pleasure, and quality being included in the choice criteria. In choosing pudding, the respondents considered the well-being of family members, and indulged their family members or themselves.

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This paper critically evaluates the vulnerability of Indian cities to climate change in the context of sustainable development. City-scale indicators are developed for multiple dimensions of security and vulnerability. Factor analysis is employed to construct a vulnerability ranking of 46 major Indian cities. The analysis reveals that high aggregate levels of wealth do not necessarily make a city less vulnerable. Two, cities with diversified economic opportunities could adapt better to the new risks posed by climate change, than cities with unipolar opportunities. Three, highly polluted cities are more vulnerable to the health impacts of climate change, and cities with severe groundwater depletion will find it difficult to cope with increased rainfall variability. Policy and sustainability issues are discussed for these results.

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The influence of microstructure and texture developed by different modes of hot cross-rolling on in-plane anisotropy (A (IP)) of yield strength, work hardening behavior, and anisotropy of Knoop hardness (KHN) yield locus has been investigated. The A (IP) and work hardening behavior are evaluated by tensile testing at 0 deg, 45 deg, and 90 deg to the rolling direction, while yield loci have been generated by directional KHN measurements. It has been observed that specimens especially in the peak-aged temper, in spite of having a strong, rotated Brass texture, show low A (IP). The results are discussed on the basis of Schmid factor analyses in conjunction with microstructural features, namely grain morphology and precipitation effects. For the specimen having a single-component texture, the yield strength variation as a function of orientation can be rationalized by the Schmid factor analysis of a perfectly textured material behaving as a quasi-single crystal. The work hardening behavior is significantly affected by the presence of solute in the matrix and the state of precipitation rather than texture, while yield loci derived from KHN measurements reiterate the low anisotropy of the materials. Theoretic yield loci calculated from the texture data using the visco-plastic self-consistent model and Hill's anisotropic equation are compared with that obtained experimentally.

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We performed Gaussian network model based normal mode analysis of 3-dimensional structures of multiple active and inactive forms of protein kinases. In 14 different kinases, a more number of residues (1095) show higher structural fluctuations in inactive states than those in active states (525), suggesting that, in general, mobility of inactive states is higher than active states. This statistically significant difference is consistent with higher crystallographic B-factors and conformational energies for inactive than active states, suggesting lower stability of inactive forms. Only a small number of inactive conformations with the DFG motif in the ``in'' state were found to have fluctuation magnitudes comparable to the active conformation. Therefore our study reports for the first time, intrinsic higher structural fluctuation for almost all inactive conformations compared to the active forms. Regions with higher fluctuations in the inactive states are often localized to the aC-helix, aG-helix and activation loop which are involved in the regulation and/or in structural transitions between active and inactive states. Further analysis of 476 kinase structures involved in interactions with another domain/protein showed that many of the regions with higher inactive-state fluctuation correspond to contact interfaces. We also performed extensive GNM analysis of (i) insulin receptor kinase bound to another protein and (ii) holo and apo forms of active and inactive conformations followed by multi-factor analysis of variance. We conclude that binding of small molecules or other domains/proteins reduce the extent of fluctuation irrespective of active or inactive forms. Finally, we show that the perceived fluctuations serve as a useful input to predict the functional state of a kinase.

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Resumen: Se aplicó el Modelo de Crédito Parcial (MCP) de la Teoría de Respuesta al Ítem (TRI) al análisis de ítems de una escala que mide Afecto hacia la Matemática. Esta variable describe el interés de los estudiantes de Psicología por involucrarse en actividades vinculadas a la matemática y los sentimientos asociados al uso de sus conceptos. La prueba consta de 8 ítems con formato de respuesta Likert de 6 opciones. Participaron 1875 estudiantes de Psicología de la Universidad de Buenos Aires (Argentina) de los cuales un 82% fueron mujeres. El análisis de la consistencia interna brindó un índice altamente satisfactorio (Alfa = .91). Se verificó la condición de unidimensionalidad requerida por el modelo mediante un análisis factorial exploratorio. Todos los análisis basados sobre la TRI se realizaron con el programa Winsteps. La estimación de los parámetros del modelo se efectuó por Máxima Verosimilitud Conjunta. El ajuste del MCP fue satisfactorio para todos los ítems. La Función de Información del Test fue elevada en un rango amplio de niveles del rasgo latente. Un ítem presentó una inversión en dos parámetros de umbral. Como consecuencia, 1 de las 6 categorías del ítem no fue máximamente probable en ningún intervalo de la escala del rasgo latente. Se analizan las implicancias de este hallazgo en la evaluación de la calidad psicométrica del ítem. Los resultados de este estudio permitieron profundizar el análisis del constructo y aportaron evidencias de validez basadas en las estructura interna de la escala

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The Biscayne Bay Benthic Sampling Program was divided into two phases. In Phase I, sixty sampling stations were established in Biscayne Bay (including Dumfoundling Bay and Card Sound) representing diverse habitats. The stations were visited in the wet season (late fall of 1981) and in the dry season (midwinter of 1982). At each station certain abiotic conditions were measured or estimated. These included depth, sources of freshwater inflow and pollution, bottom characteristics, current direction and speed, surface and bottom temperature, salinity and dissolved oxygen, and water clarity was estimated with a secchi disk. Seagrass blades and macroalgae were counted in a 0.1-m2 grid placed so as to best represent the bottom community within a 50-foot radius. Underwater 35-mm photographs were made of the bottom using flash apparatus. Benthic samples were collected using a petite Ponar dredge. These samples were washed through a 5-mm mesh screen, fixed in formalin in the field, and later sorted and identified by experts to a pre-agreed taxonomic level. During the wet season sampling period, a nonquantitative one-meter wide trawl was made of the epibenthic community. These samples were also washed, fixed, sorted and identified. During the dry season sampling period, sediment cores were collected at each station not located on bare rock. These cores were analyzed for sediment size and organic composition by personnel of the University of Miami. Data resulting from the sampling were entered into a computer. These data were subjected to cluster analyses, Shannon-Weaver diversity analysis, multiple regression analysis of variance and covariance, and factor analysis. In Phase II of the program, fifteen stations were selected from among the sixty of Phase I. These stations were sampled quarterly. At each quarter, five Petite Ponar dredge samples were collected from each station. As in Phase I, observations and measurements, including seagrass blade counts, were made at each station. In Phase II, polychaete specimens collected were given to a separate contractor for analysis to the species level. These analyses included mean, standard deviation, coefficient of dispersion, percent of total, and numeric rank for each organism in each station as well as number of species, Shannon-Weaver taxa diversity, and dominance (the compliment of Simpson's Index) for each station. Multiple regression analysis of variance and covariance, and factor analysis were applied to the data to determine effect of abiotic factors measured at each station. (PDF contains 96 pages)

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ENGLISH: Samples of yellowfin tuna, Thunnus albacares, collected from five areas of the Pacific Ocean (Mexico, Ecuador, Australia, Japan, and Hawaii) between January and May of 1988 and 1990 were examined for spatiotemporal variation in morphometric characters and gill-raker counts. 'Iwo-factor analysis of variance, with area and year treated as grouping factors, indicated a significant difference in the means of the total gill-raker counts among fish from different areas, but no significant difference between fish caught in different years. The morphometric data were adjusted by allometric formulae to remove size effects. The correct classification rates for the five groups, using discriminant function analysis, based on adjusted morphometric characters, were 77.60/0 for the samples from 1988 and 74.40/0 for those from 1990. These are 72.00/0 and 68.00/0 (Cohen's kappa statistic) better than would have occurred chance. The pattern of geographic variability, however, is unstable for these two years, thus requiring separate discriminant functions for each year. Although there is annual variability in the morphometric characters, these results demonstrate that the stocks examined are morphometrically distinguishable and that their phenetic relationships reflect their geographic origin. SPANISH: Se examinaron muestras de atún aleta amarilla, Thunnus albacares, tomadas de cinco áreas del Océano Pacífico (México, Ecuador, Australia, Japón, y Hawaii) entre enero y mayo de 1988 y 1990, para descubrir variaciones espaciotemporales en las características morfométricas y los conteos de branquiespinas. Un análisis de varianza de dos factores, con área y año como factores de agrupación, indicó una diferencia significativa en los promedios de los conteos de branquiespinas totales entre peces de distintas áreas, pero ninguna entre peces capturados en distintos años. Se ajustaron los datos morfométricos con fórmulas alométricas para eliminar los efectos de la talla del pez. En un análisis de función discriminante, las tasas de clasificación correcta de los cinco grupos, basadas en características morfométricas ajustadas, fueron 77.60/0 para las muestras de 1988 y 74.40/0 para aquellas de 1990. Estas cifras son 72.00/0 y 68.00/0 (estadístico de kappa de Cohen) mejores de lo que se hubiera obtenido al azar. Sin embargo, la variabilidad geográfica es inestable en estos dos años, requiriendo por lo tanto funciones discriminantes separadas para cada año. Aunque existe variabilidad anual en las características morfométricas, estos resultados demuestran que los stocks examinados son morfamétricamente distinguibles, y que su relación fenética refleja su origen geográfico. (PDF contains 31 pages.)