10 resultados para 140304 Panel Data Analysis

em Archivo Digital para la Docencia y la Investigación - Repositorio Institucional de la Universidad del País Vasco


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Published as an article in: Oxford Bulletin of Economics and Statistics, 2009, vol. 71, issue 4, pages 491-518.

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DNA microarray, or DNA chip, is a technology that allows us to obtain the expression level of many genes in a single experiment. The fact that numerical expression values can be easily obtained gives us the possibility to use multiple statistical techniques of data analysis. In this project microarray data is obtained from Gene Expression Omnibus, the repository of National Center for Biotechnology Information (NCBI). Then, the noise is removed and data is normalized, also we use hypothesis tests to find the most relevant genes that may be involved in a disease and use machine learning methods like KNN, Random Forest or Kmeans. For performing the analysis we use Bioconductor, packages in R for the analysis of biological data, and we conduct a case study in Alzheimer disease. The complete code can be found in https://github.com/alberto-poncelas/ bioc-alzheimer

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[ES] Recientemente estudios previos han comenzado a plantear la posible relación entre el fenómeno de la internacionalización y responsabilidad social corporativa de las organizaciones. En este trabajo analizamos en qué medida la internacionalización contribuye a una mejora sustancial del desempeño social de las empresas. Usando una muestra de 102 empresas estadounidenses de los sectores químico, energético y de maquinaria industrial, nuestros resultados muestran que no todas las dimensiones de la internacionalización permiten a las empresas adquirir conocimiento valioso que conduzca a una mejora de su desempeño social. Concretamente, comprobamos que, mientras el porcentaje de ventas en mercados extranjeros y la diversificación internacional cultural favorecen la puesta en marcha de prácticas de responsabilidad social corporativa avanzadas que redundan en un mejor desempeño social (cumpliendo con las demandas sociales de los grupos de interés de los distintos mercados donde operan), la diversificación internacional geográfica no tiene efecto directo en el desempeño social de las empresas. Por tanto, no es tan importante el número de mercados donde la empresa actúa, sino el grado de diferenciación cultural existente entre los mismos lo que hace que la propia empresa mejore su desempeño social. El presente trabajo incluye implicaciones relevantes para el mundo académico, directivos y reguladores públicos.

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Background: Malignancies arising in the large bowel cause the second largest number of deaths from cancer in the Western World. Despite progresses made during the last decades, colorectal cancer remains one of the most frequent and deadly neoplasias in the western countries. Methods: A genomic study of human colorectal cancer has been carried out on a total of 31 tumoral samples, corresponding to different stages of the disease, and 33 non-tumoral samples. The study was carried out by hybridisation of the tumour samples against a reference pool of non-tumoral samples using Agilent Human 1A 60- mer oligo microarrays. The results obtained were validated by qRT-PCR. In the subsequent bioinformatics analysis, gene networks by means of Bayesian classifiers, variable selection and bootstrap resampling were built. The consensus among all the induced models produced a hierarchy of dependences and, thus, of variables. Results: After an exhaustive process of pre-processing to ensure data quality–lost values imputation, probes quality, data smoothing and intraclass variability filtering–the final dataset comprised a total of 8, 104 probes. Next, a supervised classification approach and data analysis was carried out to obtain the most relevant genes. Two of them are directly involved in cancer progression and in particular in colorectal cancer. Finally, a supervised classifier was induced to classify new unseen samples. Conclusions: We have developed a tentative model for the diagnosis of colorectal cancer based on a biomarker panel. Our results indicate that the gene profile described herein can discriminate between non-cancerous and cancerous samples with 94.45% accuracy using different supervised classifiers (AUC values in the range of 0.997 and 0.955).

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This paper reviews the methods for measuring the economic cost of conflict. Estimating the economic costs of conflict requires a counterfactual calculation, which makes this a very difficult task. Social researchers have resorted to different estimation methods depending on the particular effect in question. The method used in each case depends on the units being analyzed (firms, sectors, regions or countries), the outcome variable under study (aggregate output, market valuation of firms, market shares, etc.) and data availability (a single cross-section, time series or panel data). This paper reviews existing methods used in the literature to assess the economic impact of conflict: cost accounting, cross-section methods, time series methods, panel data methods, gravity models, event studies, natural experiments and comparative case studies. The paper ends with a discussion of cost estimates and directions for further research.

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[EN] The concept of image in its different aspects is very important in today s society as well as in the business management field. Some authors reports that most of the studies that measure image do not take into account neither previous theoretical and conceptual models nor other possible empirical evidence alternatives. Given this need, a research regarding the concept of brand image applied to shopping malls was conducted based on the conceptual model of the consumer cognitive response in order to empirically explore and contrast it. For this reason, a survey was applied to 420 consumers in five shopping malls in Bogotá, achieving a database of 3.749 cases. The results show attribute-shopping mall associations expressed in unique, differentiated, and notorious vocabulary obtained applying lexicometric and multivariate analysis techniques. Attribute-shopping mall associations such as spacious , good location , good variety of stores , and the existence of movie theaters . Finally, this research aims to potentially improve the management of shopping malls and increase their attractiveness and customer loyalty by applying the development of service quality systems, integral communication, segmentation, and positioning.

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185 p.

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This paper investigates whether the effect of political institutions on sectoral economic performance is determined by the level of technological development of industries. Building on previous studies on the linkages among political institutions, technology and economic growth, we employ the dynamic panel Generalized Method of Moments (GMM) estimator for a sample of 4,134 country-industries from 61 industries and 89 countries over the 1990-2010 period. Our main findings suggest that changes of political institutions towards higher levels of democracy, political rights and civil liberties enhance economic growth in technologically developed industries. On the contrary, the same institutional changes might retard economic growth of those industries that are below a technological development threshold. Overall, these results give evidence of a technologically conditioned nature of political institutions to be growth-promoting.

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[ES] Durante la última década surge un interés por el estudio de la estructura de propiedad como elemento determinante de la diversificación. Sin embargo, existe una carencia de investigaciones que analicen la influencia de la naturaleza del último propietario en el nivel y tipo de diversificación. Por ello, el objeto del presente trabajo es analizar las estrategias de diversificación empleadas por los grandes grupos empresariales españoles cuya empresa matriz cotiza en los mercados de valores, estudiando las diferencias existentes entre grupos familiares y no familiares, y considerando en estos últimos la naturaleza del último propietario. Se parte de una muestra de noventa y nueve grupos empresariales, donde se identifican las compañías que constituyen el grupo empresarial, siendo empleadas como metodologías econométricas los modelos logísticos binomiales y los modelos datos panel. Los resultados muestran como la naturaleza familiar del grupo influye positivamente en la especialización y en el empleo de estrategias de diversificación relacionada, y negativamente en el empleo de estrategias de diversificación no relacionada. Los grupos familiares difieren en mayor medida de aquellos grupos no familiares donde no existe un accionista de referencia que pueda ejercer el control efectivo del grupo y la dispersión de la propiedad es mayor, los denominados grupos sin control efectivo . La investigación permite profundizar en el análisis de las diferencias existentes entre grupos familiares y no familiares, y más concretamente en el ámbito de las estrategias de crecimiento, considerando la naturaleza del último propietario de los grupos no familiares.