Varying coefficient models: empirical likelihood and stability tests

RESUMEN: El objetivo de esta tesis doctoral es aplicar y desarrollar técnicas de inferencia estadística para modelos de coeficientes variables. Por un lado, se investigan técnicas de inferencia estadística basadas en la verosimilitud empírica para modelos de coeficientes variables continuos y discretos, en un contexto de datos de panel con efectos fijos. Primero, demostramos que el ratio de verosimilitud empírica para el coeficiente variable es asintóticamente chi-cuadrado. El ratio es invariable a cambios de escala y no es necesaria la estimación de la varianza. Como subproductos, proponemos los estimadores de máxima verosimilitud empírica de los coeficientes variables. También obtenemos la distribución asintótica de estos estimadores y proponemos algunos procedimientos para calcular los bandwidths empíricamente. Para demostrar la viabilidad de la técnica y analizar sus propiedades en muestras finitas, implementamos un ejercicio de simulación de Monte Carlo, y también proponemos un análisis empírico. Sería interesante ampliar los resultados obtenidos a modelos de coeficientes variables con datos mixtos. Por otro lado, se propone un test para detectar constancia de parámetros en modelos de coeficientes variables. Para regresores exógenos, el procedimiento para relaizar el contraste se asemeja a los contrastes de unión-intersección (U-I) de estabilidad de parámetros en series temporales. El test puede aplicarse para verificar la especificación de modelización de efectos interactivos en modelos de regresión lineales. Debido a que el estadístico de contraste no es asintóticamente pivotal, los valores críticos y los p-valores se estiman utilizando la técnica del bootstrap. Para regresores endógenos, el test se define como un ratio de verosimilitud generalizado que se enfoca en la comparación de la suma de cuadrada de los residuos del modelo restringido y no restringido. Como subproducto, y mimetizando la literatura de variables instrumentales, proponemos utilizar un procedimiento de estimación en tres etapas para estimar los coeficientes variables; también establecemos las propiedades asintóticas de los estimadores. Para terminar, investigamos las propiedades en muestras finitas de nuestro test por medio de experimentos de Monte Carlo. Aunque los resultados son prometedores, sería interesante ampliar los resultados al marco de datos de panel.ABSTRACT: The goal of this doctoral dissertation is to apply and develop inference techniques for varying coefficient models. On the one hand, empirical likelihood based inference for categorical and continuous varying coefficient models, under a panel data with fixed effects framework, is investigated. First, we show that the naive empirical likelihood ratio is asymptotically standard chi-squared. The ratio is self-scale invariant and the plug-in estimate of the limiting variance is not needed. As a by product, we propose empirical maximum likehood estimators for varying coefficients. We also obtain the asymptotic distribution of these estimators and we propose some procedures to calculate the bandwidths empirically. Furthermore, a non parametric version of the Wilk’s theorem is derived. To show the feasibility of the technique and to analyse its small sample properties we implement a Monte Carlo simulation exercise and we also illustrated the proposed technique in an empirical analysis. On the other hand, we propose tests for constancy of coefficients in varying coefficients models under different settings. For exogenous regressors, the testing procedure resembles in spirit the union-intersection parameter stability tests in time series. The test can be applied to model specification checks of interactive effects in linear regression models. Because test statistics are not asymptotically pivotal, critical values and p-values are estimated using a bootstrap technique. For the endogenous case, the testing procedure is defined as a generalized likelihood ratio that focus on the comparison of the restricted and unrestricted sum of squared residuals. As a by product, and resembling the instrumental variable literature, we propose to use a three stages estimation procedure to estimate the varying coefficients; we also establish the asymptotic properties of the estimators. The finite sample properties of the test are investigated by means of Monte Carlo experiments.Next I would like to mention the research project ECO2013-48326-C2-2-P, "Modelos paramétricos y semi-paramétricos de riesgos dependientes: especificación y contraste" funded by Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia / Spanish Ministry of Economy and Competitiveness, thanks to which this PhD thesis has been possible, and thank Professor Jose Maria Sarabia Alegria and all the people involved in the project for their kindness, trust and advice

Managing Interacting Criteria: Application to Environmental Evaluation Practices

The need for organizations to evaluate their environmental practices has been recently increasing. This fact has led to the development of many approaches to appraise such practices. In this paper, a novel decision model to evaluate company’s environmental practices is proposed to improve traditional evaluation process in different facets. Firstly, different reviewers’ collectives related to the company’s activity are taken into account in the process to increase company internal efficiency and external legitimacy. Secondly, following the standard ISO 14031, two general categories of environmental performance indicators, management and operational, are considered. Thirdly, since the assumption of independence among environmental indicators is rarely verified in environmental context, an aggregation operator to bear in mind the relationship among such indicators in the evaluation results is proposed. Finally, this new model integrates quantitative and qualitative information with different scales using a multi-granular linguistic model that allows to adapt diverse evaluation scales according to appraisers’ knowledge

Testing Constancy in Varying Coefficient Models

This article proposes tests for constancy of coefficients in semi-varying coefficients models. The testing procedure resembles in spirit the union-intersection parameter stability tests in time series, where observations are sorted according to the explanatory variable responsible for the coefficients varying. The test can be applied to model specification checks of interactive effects in linear regression models. Because test statistics are not asymptotically pivotal, critical values and p-values are estimated using a bootstrap technique. The finite sample properties of the test are investigated by means of Monte Carlo experiments, where the new proposal is compared to existing tests based on smooth estimates of the unrestricted model. We also report an application to returns of education modelingResearch funded by Ministerio Economía y Competitividad (Spain), ECO2017-86675-P & MDM 2014-0431, and by Comunidad de Madrid (Spain), MadEco-CM S2015/HUM-3444

Propuesta de implementación de un sistema de gestión de producción y logística para reducir los costos operacionales de la empresa de calzados Abele S. A. C – Trujillo

El presente trabajo tuvo como objetivo general reducir los costos operacionales de la empresa de calzados Abele S.A.C mediante la propuesta de implementación de un sistema de Producción y Logística en la empresa de calzado Abele S.A.C. Para comenzar se realizó un diagnóstico de la situación actual de la empresa de calzados Abele S.A.C. por cada área de estudio. Se seleccionó el área de Producción y Logística ya que se diagnosticó que eran las de mayor criticidad en la empresa, debido a la perdida de dinero en productos por la falta de planificación y adquisición de materiales generando altos costos en el área de logística. Culminada la etapa de la identificación de los problemas, se procedió a redactar el diagnóstico de la empresa, en el cual se tomó en cuenta todas las problemáticas que se evidenciaron para demostrar lo mencionado anteriormente. Posteriormente se realizó la priorización de las causas raíces mediante el diagrama de Pareto para determinar el impacto económico que genera en la empresa esta problemática representado en pérdidas monetarias de S/.39,202.86 nuevos soles anuales. Adicionalmente en el trabajo aplicativo se explica a detalle el proceso productivo de las sandalias A101 incluido los tiempos de cada proceso, además se detallan el tipo de maquinaria que se requieren para el proceso y las herramientas que se utilizan. En la empresa que se trabajó se presentan algunos de los problemas que están influenciando negativamente en sus costos: Falta de planificación en la producción. Falta de control de documentos en la producción. No se cuenta con un adecuado requerimiento de materiales. Falta de orden en almacenamiento de materia prima y producto terminado. Falta de capacitación del personal. Ausencia de formatos para el control de procesos logísticos. No se cuenta con un adecuado abastecimiento de materiales. Falta de indicadores de control de inventario.Luis Arteaga, Lissy; Zavaleta Quiliche, Fiorella viii Para ello se detallaron las siguientes propuestas de mejora como: el sistema MRP II, herramienta 5S, Kárdex y el Plan de capacitación que fueron evaluadas económica y financieramente. Finalmente, y con toda la información analizada y recolectada; y a partir del diagnóstico que ha sido elaborado, se presentará un análisis de los resultados y discusión para poder corroborar con datos cuantitativos las evidencias presentadas y así lograr con la propuesta de mejora en las áreas de Producción y Logística de la empresa de Calzados Abele S.A.C reducir los costos operacionales obteniendo como resultado un VAN de S/19,231.94, un TIR de 61.39% y un Beneficio/Costo de 1.7.The objective of the present work was to reduce the operational costs of the shoe company Abele S.A.C by proposing the implementation of an MRP II system in the Logistics and Production of sandals A101. To begin, a diagnosis was made of the current situation of the shoe company Abele S.A.C for each study area. The Production and Logistics area was selected because it was diagnosed that they were the most critical in the company, due to the loss of money in products due to the lack of planning and acquisition of materials generating high costs in the logistics area. Once the problem identification stage had been completed, a diagnosis of the company was made, which took into account all the problems that were evidenced to demonstrate the aforementioned. Subsequently, the root causes were prioritized through the Pareto diagram to determine the economic impact generated by the company in this problem represented by monetary losses of S /.39,202.86 New annual suns. In addition, the application process explains the production process of the A101 sandals, including the times of each process, as well as the type of machinery required for the process and the tools used. In the company that worked, some of the problems that are negatively influencing their costs are presented: Lack of planning in production. Lack of document control in production. There is no adequate material requirement. Lack of order in storage of raw material and finished product. Lack of staff training. Absence of formats for the control of logistics processes. There is no adequate supply of materials. Lack of inventory control indicators.Luis Arteaga, Lissy; Zavaleta Quiliche, Fiorella x The following improvement proposals were detailed as follows: the MRP II system, 5S tool, Kárdex and the Training Plan, which were evaluated economically and financially. Finally, with all the information analyzed and collected; And from the diagnosis that has been elaborated, an analysis of the results and discussion will be presented to be able to corroborate with quantitative data the evidences presented and thus achieve with the proposal of improvement in the Production and Logistics areas of the company of “Calzados Abele S.A.C.” reduce The operational costs resulting in a NPV of S/19,231.94, a TIR of 61.39% and a Profit / Cost of 1.7

Empirical likelihood based inference for fixed effects varying coefficient

ABSTRACT: In this paper local empirical likelihood-based inference for non-parametric varying coefficient panel data models with fixed effects is investigated. First, we show that the naive empirical likelihood ratio is asymptotically standard chi-squared when undersmoothing is employed. The ratio is self-scale invariant and the plug-in estimate of the limiting variance is not needed. Second, mean-corrected and residual-adjusted empirical likelihood ratios are proposed. The main interest of these techniques is that without undersmoothing, both also have standard chi-squared limit distributions. As a by product, we propose also two empirical maximum likelihood estimators of the varying coefficient models and their derivatives. We also obtain the asymptotic distribution of these estimators. Furthermore, a non parametric version of the Wilk?s theorem is derived. To show the feasibility of the technique and to analyse its small sample properties, using empirical likelihood-based inference we implement a Monte Carlo simulation exercise and we also illustrated the proposed technique in an empirical analysis about the production efficiency of the European Union?s companies

Empirical likelihood based inference for a categorical varying-coefficient panel data model with fixed effects

ABSTRACT: In this paper local empirical likelihood-based inference for nonparametric categorical varying coefficient panel data models with fixed effects under cross-sectional dependence is investigated. First, we show that the naive empirical likelihood ratio is asymptotically standard chi-squared using a nonparametric version of Wilks? theorem. The ratio is self-scale invariant and the plug-in estimate of the limiting variance is not needed. As a by product, we propose also an empirical maximum likelihood estimator of the categorical varying coefficient model and we obtain the asymptotic distribution of this estimator. We also illustrated the proposed technique in an application that reports estimates of strike activities from 17 OECD countries for the period 1951-85

Consulting report – Toulouse Lautrec

Toulouse Lautrec is an Escuela de Educación Superior in Peru, the first institution in the country to obtain the SUNEDU licensing to operate as an escuela. It also belongs to the Educa group, to which also belongs Universidad de Ciencias y Artes de América Latina and the CERTUS Institute. The educational center was founded in 1983, being one of the first to focus on creative careers. Currently, TLS offers specialization in six subjects. Also, to offer a quality education, the company has two business units, Antegrado and Educación Continua. The company employs more than 900 professors, with a student body of 7,500 and more than 6,000 graduates. In recent years, one of the main challenges for TLS is to improve the image and profitability of Educación Continua business unit, which operates in the four buildings that the company has, sharing spaces with Antegrado in the campuses of Santiago de Surco and Magdalena, while at the sede of San Miguel and Independencia it operates 100%. To achieve the objective, the CENTRUM consulting team held meetings with the company to identify the problem and propose the optimal solution. After conducting an analysis of the company, it was determined that the problem to be solved is the low percentage of use of classrooms, mainly at the sede of San Miguel. In the course of the consultancy and with the commitment of TLS representatives, it was proposed to establish an innovation center at San Miguel. This implies enabling co-working spaces. The budget to implement this proposal amounts to S/608,600, and will give as a result a net present value of S/495,538. It is expected to develop this plan in September 2019 and have the spaces enabled by January 2020. The result of this proposal will bring sustained growth in the operating margin of sede San Miguel.Toulouse Lautrec es una escuela de educación superior en el Perú, primera institución en el país en conseguir el licenciamiento de SUNEDU para operar como escuela. Además, pertenece al grupo Educa, al cual también pertenecen la Universidad de Ciencias y Artes de América Latina y el instituto CERTUS. El centro educativo fue fundado en el año 1983, siendo uno de los primeros en enfocarse en carreras creativas. En la actualidad, TLS ofrece especialización en seis temas. Asimismo, para ofrecer una educación de calidad, la empresa tiene dos unidades de negocio, Antegrado y Educación Continua. La empresa emplea a más de 900 docentes, con un alumnado de 7,500 estudiantes y más de 6,000 graduados. En los últimos años, uno de los principales retos para TLS es mejorar la imagen y rentabilidad de la unidad de negocio de Educación Continua, la cual opera en los cuatro edificios que tiene la empresa, compartiendo espacios con Antegrado en los campuses de Santiago de Surco y Magdalena, mientras que en las sedes de San Miguel e Independencia opera al 100%. Para lograr el objetivo, el equipo de consultoría de CENTRUM, sostuvo reuniones con la empresa para identificar el problema y proponer la solución óptima. Luego de realizar un análisis de la empresa, se determinó que el problema a solucionar es el bajo porcentaje de utilización de aulas en las aulas, principalmente en la sede de San Miguel. En el transcurso de la consultoría y con el compromiso de los representantes de TLS, se propuso establecer un centro de innovación en la sede. Esto implica habilitar espacios de co-working. El presupuesto para implementar esta propuesta suma S/608,600 y dará como resultado un valor presente neto de S/495,538. Se espera desarrollar este plan en el mes de septiembre del 2019 y tener los espacios habilitados para enero del 2020. El resultado de esta propuesta, traerá un crecimiento sostenido en el margen operativo de la sede San Miguel.Tesi