Andres Ramírez

Andres Ramírez
Universidad EAFIT · Department of Economics

PhD Statistics

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96
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Introduction
Skills and Expertise

Publications

Publications (96)
Article
Despite colossal economic and human losses caused by conflict and violence, designing effective policies to avoid conflict remains challenging. While the literature has proposed a voluminous set of candidate predictors, their robustness is questionable and model uncertainty masks the true drivers of conflicts and wars. Considering a comprehensive s...
Article
We examine the effect of an integrity pilot campaign on undergraduates' behavior. As with many costly small-scale experiments and pilot programs, our statistical inference has to rely on small sample size. To tackle this issue, we perform a Bayesian retrospective power analysis. In our setup, a lecturer intentionally makes mistakes that favors stud...
Article
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Food price elasticities (PEs) are essential for evaluating the impacts of food pricing interventions to improve dietary and health outcomes. This paper innovates the use of experimental purchasing data from a recent New Zealand virtual supermarket experiment to estimate PEs for a large set of disaggregated foods across major food groups relevant fo...
Preprint
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We provide a novel inferential framework to estimate the exact affine Stone index (EASI) model, and analyze welfare implications due to price changes caused by taxes. Our inferential framework is based on a non-parametric specification of the stochastic errors in the EASI incomplete demand system using Dirichlet processes. Our proposal enables to i...
Article
Proper scoring rules are used to assess the out-of-sample accuracy of probabilistic forecasts, with different scoring rules rewarding distinct aspects of forecast performance. Herein, we re-investigate the practice of using proper scoring rules to produce probabilistic forecasts that are ‘optimal’ according to a given score and assess when their ou...
Article
Internet adoption fosters economic growth and development. Specifying policy control drivers is particularly relevant for developing countries. However, there is no consensus on the most relevant variables. We explored 33.6 million potential models to identify the most important determinants of household internet adoption using stochastic search va...
Article
This paper proposes a Bayesian approach to perform inference in the exact affine Stone index (EASI) demand system that was proposed by Lewbel and Pendakur (2009), while taking into account nonlinearity and endogeneity. A Bayesian approach enables us to easily handle censored data, test and impose inequality restrictions (strict cost monotonicity) a...
Article
Full-text available
We analyze the treatment effects due to patients’ status, covered or uncovered by the subsidized health program in Medellín (Colombia), on the number of preventive health care visits to physicians. We use a Bayesian endogenous switching model that allows interaction effects as well as endogeneity due to patients’ status. This framework allows the c...
Preprint
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This paper proposes a Bayesian approach to perform inference regarding the size of hidden populations at analytical region using reported statistics. To do so, we propose a specification taking into account one-sided error components and spatial effects within a panel data structure. Our simulation exercises suggest good finite sample performance....
Preprint
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We propose a simple approach to optimally select the number of control units in k nearest neighbors (kNN) algorithm focusing in minimizing the mean squared error for the average treatment effects. Our approach is non-parametric where confidence intervals for the treatment effects were calculated using asymptotic results with bias correction. Simula...
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We extend the dynamic model averaging framework for dynamic logistic regression proposed by McCormick et al. (Biometrics 68(1):23–30, 2012) to incorporate variable selection. This method of accommodating uncertainty regarding predictors is particularly appealing in scenarios where relevant predictors change through time, and there are potentially m...
Article
We propose a Bayesian one-stage approach to estimate the effect of inefficiency on the time to failure (bankruptcy) of U.S. commercial banks. We do so combining stochastic frontier and proportional hazards settings. Most of the existing literature use two-stage methods which may yield inefficient, biased, and inconsistent estimates. Our proposal se...
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The mainstream in finance tackles portfolio selection based on a plug-in approach without consideration of the main objective of the inferential situation. We propose minimum expected loss (MELO) estimators for portfolio selection that explicitly consider the trading rule of interest. The asymptotic properties of our MELO proposal are similar to th...
Article
We propose a Bayesian estimation procedure for the generalized Bass model that is used in product diffusion models. Our method forecasts product sales early based on previous similar markets; that is, we obtain pre-launch forecasts by analogy. We compare our forecasting proposal to traditional estimation approaches, and alternative new product diff...
Preprint
Full-text available
We propose a Bayesian one-stage approach to estimate the effect of inefficiency on the time to failure (bankruptcy) of U.S. commercial banks. We do so combining stochastic frontier and proportional hazards settings. Most of the existing literature uses two-stage methods which may yield inefficient, biased, and inconsistent estimates. Our proposal s...
Article
Central to many inferential situations is the estimation of rational functions of parameters. The mainstream in statistics and econometrics estimates these quantities based on the plug‐in approach without consideration of the main objective of the inferential situation. We propose the Bayesian Minimum Expected Loss (MELO) approach focusing explicit...
Article
This article tries to uncover the drivers of soccer players’ market value in the five major European soccer leagues taking into account model uncertainty (variable selection) in a framework with 35 billion potential models. For this purpose, we use a hedonic regression framework and implement Bayesian model averaging (BMA) through Markov chain Mont...
Article
Since 1980, the world has been undergoing a continuous process of integration in different aspects, and financial markets are no exception to this development. Even though global integration is gradual, specific events can accelerate this trend. This article shows that after the financial crisis of 2008, which was especially acute in the United Sta...
Preprint
Full-text available
Food price elasticities (PE) are essential for evaluating impacts of food pricing interventions. Existing econometric estimates of food PEs are often poor, being based on single observational data sets without much variation in prices and failing to utilise prior information. In order to provide better PE estimates for policy analysis, this paper i...
Preprint
Full-text available
Central to many inferential situations is the estimation of rational functions of parameters. The mainstream in statistics and econometrics estimates these quantities based on the plug-in approach without consideration of the main objective of the inferential situation. We propose the Bayesian Minimum Expected Loss (MELO) approach focusing explicit...
Article
In this paper, we analyze the effect on posterior parameter distributions of four possible alternative prior distributions, namely Normal-Inverse Gamma, Normal-Scaled Beta two, Student’s t-Inverse Gamma and Student’s t-Scaled Beta two. We show the effects of these prior distributions when there is apparently conflict between the sample information...
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The gravity model is a workhorse tool that has been widely used in international trade. However, one empirical question that frequently arises is related to the conceptualization and measurement of an economic distance index. Our study proposes an index based on Multiple Factor Analysis. This technique summarizes information related to the geograph...
Article
The interplay between the Bayesian and Frequentist approaches: a general nesting spatial panel-data model. Spatial Economic Analysis. An econometric framework mixing the Frequentist and Bayesian approaches is proposed in order to estimate a general nesting spatial model. First, it avoids specific dependency structures between unobserved heterogenei...
Article
We introduce a Bayesian instrumental variable procedure with spatial random effects that handles endogeneity, and spatial dependence with unobserved heterogeneity. We find through a limited Monte Carlo experiment that our proposal works well in terms of point estimates and prediction. We apply our method to analyze the welfare effects generated by...
Thesis
Full-text available
In this paper we examine which macroeconomic and financial variables have most predictive power for the target repo rate decisions made by the Federal Reserve. We conduct the analysis for the FOMC decisions during the period June 1998-April 2015 using dynamic logistic models with dynamic Bayesian Model Averaging that allows to perform predictions i...
Article
This paper uses Bayesian model averaging to uncover the true determinants of export diversification among 36 potential factors, and thus 236 potential models. Using data from 2001 to 2010, our results reveal two strong predictors: Primary school enrollment (99.7% posterior inclusion probability in the true model) raises export diversification, wher...
Article
The world meat market demands competitiveness and optimal livestock replacement decisions can help to achieve this goal. We introduce a novel discrete stochastic dynamic programming framework to support a manager’s decision-making process of whether to sell or keep fattening animals in the beef sector. In particular, our proposal uses a non-convex...
Article
We introduce a Bayesian instrumental variable procedure with spatial random effects that handles endogeneity, and spatial dependence with unobserved heterogeneity. We take into account the endogeneity through a system of simultaneous equations where a conditional correlation between the stochastic errors captures the endogeneity, and exclusion rest...
Article
In this paper we analyze the effect of four possible alternatives regarding the prior distributions in a linear model with autoregressive errors to predict piped water consumption: Normal-Gamma, Normal-Scaled Beta two, Studentized-Gamma and Student's t-Scaled Beta two. We show the effects of these prior distributions on the posterior distributions...
Article
This paper presents several "ex ante" simulation exercises of the 2014 FIFA World Cup. Specifically, we estimate the probabilities of each national team advancing to different stages, using a basic Bayesian approach based on conjugate families. In particular, we use the Categorical-Dirichlet model in the first round and the Bernoulli-Beta model in...
Article
Full-text available
This paper uses count and binary data models with an endogenous dummy variable to evaluate the effect of the subsidized health care program in Medellin (Colombia). The subsidized program, which primarily covers poor people, is found to have a significant impact on the use of preventive medical care and hospitalization that might have a negative imp...
Article
The main objective of this paper is to identify key factors that determine the decision of an individual to become an entrepreneur in the Medellin Metropolitan Area in 2009. Using models such as Multinomial Logit and Probit, as well as Sequential Binary Logit, we assess the probability that a person makes an occupational decision to be an entrepren...
Article
Full-text available
El objetivo de este artículo es identificar determinantes que llevan a los individuos a la toma de la decisión de ser empresarios en Medellín Área Metropolitana en 2009. Mediante modelos logit y probit multinomial, y logit binario secuencial, se estima la probabilidad de que una persona tome la decisión ocupacional de ser empresario, independiente...
Article
Esta investigación estimó la elasticidad de la demanda intramolecular, marca y gené­rico, para tres patologías trazadoras, hipertensión esencial, diabetes e hiperlipidemia, en el mercado ético y privado colombiano, a partir de una especificación dinámica del modelo AIDS basado en técnicas de cointegración. La estimación de la elasticidad de la dema...
Article
Full-text available
Based on a dynamic specification of the AIDS model arisen from cointegration techniques, this research estimated the elasticity of the intra-molecular, brand and generic demand for three tracer conditions: essential hypertension, diabetes and hyperlipidemia both in the non-profit and private Colombian market. The estimate of the intra-molecular dem...
Article
The present article shows the theory implicit in the intertemporal government budget constraint. From this framework, it is run a series of simulation exercises about the public debt sustainability problem and the needed fiscal sacrifices to judge the actual level of sustainable indebtedness in some countries into Euro zone. Specifically, Greece, P...
Article
Currently, the world is facing a continuous process of integration in di�fferent aspects and fi�nancial markets are no exception to this development. Despite the fact that global integration is gradual, one can fi�nd some specfi�c events that might help to accelerate this trend. This paper shows that after the fi�nancial crisis of 2008, which mainl...
Article
Spanish Abstract: En este artículo se muestra el marco teórico implícito en la restricción presupuestaria intertemporal del gobierno. A partir de este, se realizan una serie de simulaciones sobre el problema de sostenibilidad de la deuda pública, y los sacrificios fiscales necesarios para juzgar el actual nivel de endeudamiento sostenible en alguno...
Article
The gravity model is a workhorse tool that has been widely used in international trade. However, one empirical question that frequently arises is related to the conceptualization and measurement of distance. To overcome this limitation, our study proposes an index of distance based on multivariate statistical analysis. Speci�cally, we build our ind...
Article
Currently, the world is facing a continuous process of integration in different aspects and financial markets are no exception to this development. Despite the fact that global integration is gradual, one can find some specific events that might help to accelerate this trend. This paper shows that after the financial crisis of 2008, which mainly oc...
Article
Full-text available
The main objective in this paper is to obtain reliable long-term and shortterm elasticities estimates of the beef demand in Colombia using quarterly data since 1998 until 2007. However, complexity on the decision process of consumption should be taken into account, since expenditure on a particular good is sequential. In the case of beef demand in...
Article
Identifying the true determinants of export diversification is difficult as there exists no comprehensive theoretical or empirical framework to capture all potential factors in their entirety. This paper uses Bayesian Model Averaging to uncover the true long-term roots of export diversification among 43 potential determinants, and thus 2^43 potenti...
Article
Economic tradition establishes that human beings' reproductive behaviour is based on rational actions. This theory is completely plausible; however, there is another part to this story, whatever else we may be, we are animals, and this biological heritage instinctively affects our reproductive strategy. Human beings want to extend their genes throu...
Article
Stationarity is a common assumption in statistical inference when data come from a random field, but this hypothesis has to be checked. In this paper, we build a frequency domain statistical test to check a unit root for a spatial autoregressive model, and find its asymptotic distribution. Later, we use Monte Carlo simulations to obtain the small s...
Article
Full-text available
This paper pretends to show empirical evidence of the CAPM model of Sharpe-Lintner (1964) for Colombia from 2003 to 2010, whose validation is carried out using the method of Black, Jensen and Scholes (1972) but introducing certain methodological econometric type changes associated to the requirements imposed by the used sample. Specifically, we fou...
Article
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This paper develops an analysis of Multinomial models through simulation; this was done under correct and incorrect assumptions on the data generating process. Also, it was analyzed the performance of the models under different sample sizes. It was found that a correct specified model with samples of 200 or more observations achieves estimators whi...
Article
Full-text available
The development of commercial strategies for effective cross-sell pension services may be one of the biggest challenges of pension funds. The database of the members of a Colombian mandatory pension fund was used for implementing several models that describe the impact of four characteristics of members on the probability of entering the voluntary...
Article
Full-text available
El desarrollo de estrategias comerciales para realizar ventas cruzadas efectivas de servicios pensionales, puede ser uno de los retos más grandes de los fondos de pensiones. Se utilizó la base de datos de los afiliados a un fondo de pensiones obligatorias colombiano para implementar varios modelos que describen la incidencia de cuatro característic...
Article
En este trabajo se elabora y se estima un modelo de datos de panel dinámico para determinar el efecto de algunos factores institucionales sobre el desempeño de una muestra de empresas colombianas no financieras durante el periodo 2002-2007. Los resultados indican que las empresas analizadas son sensibles a estos factores. Las instituciones relacion...
Article
Full-text available
En este trabajo se presentan los resultados de una investigación empírica sobre los cambios en la posición de mercado de las empresas colombianas, según la matriz crecimiento-participación desarrollada por la firma Boston Consulting Group. Para ello se utilizan datos de la Superintendencia de Sociedades de Colombia y se aplican modelos logit multin...
Article
Full-text available
In this paper, we estimate a dynamic panel data model to determine the effect of various institutional factors on the performance of a sample of Colombian companies during the period 2002-2007. Our results indicate that the analysed companies are affected by these factors. Institutions associated with property rights and contract compliance have si...
Article
Full-text available
Public utilities reforms in the nineties introduced institutional and methodological changes in the price regulation of electricity and water supply utilities in Colombia. This paper, in addition to outlining these changes, evaluates welfare effects through a counterfactual scenario and the measurement of equivalent variation. With the counterfactu...
Article
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Les réformes des années 90 ont introduit des changements institutionnels et méthodologiques dans la régulation tarifaire des services d�électricité et d�eau en Colombie. Cet article fait un bilan de ces changements pour évaluer ensuite le bien-être à travers le calcul de deux estimateurs : le contrefactuel et la variation équivalente. Le contrefact...
Article
Full-text available
ResumenDebido a la unificación tarifaria que se presentó en el Departamento de Antioquia en el primer semestre del año 2008 ocasionada por la adquisición del 100% de la participación accionaria de EADE por parte de EPM, se originaron una serie de implicaciones de bienestar en los usuarios del servicio de electricidad del Departamento. Específicamen...
Article
Full-text available
El presente artículo hace una comparación entre dos maneras de estimar el spread de los rendimientos de los bonos del gobierno colombiano, como son: la metodología de Nelson & Siegel y una metodología basada en el cálculo del spread a través de la Tasa Interna de Retorno de títulos transados en el mercado; para así estudiar si existe una relación s...
Article
Full-text available
El presente trabajo utiliza una Aproximación Lineal del Modelo Casi Ideal de Demanda (Linear Approximation/Almost Ideal Demand System) para examinar los gastos de los colombianos en la canasta básica, y estimar sus respectivas elasticidades precio y gasto, a partir de datos de series de tiempo para Colombia en el período de 1968-2007. Las elasticid...
Article
Spanish Abstract: En este trabajo se hace una investigacion empirica sobre los cambios en la posicion de mercado de las empresas colombianas, segun la Matriz Crecimiento-Participacion desarrollada por la firma Boston Consulting Group. Para ello se utilizan datos de la Superintendencia de Sociedades de Colombia y se aplican modelos Logit Multinomial...
Article
Spanis Abstract: Las reformas de mediados de los noventa, basadas en las leyes 142 y 143 de 1994, introdujeron cambios institucionales y metodológicos en la regulación tarifaria para los servicios de electricidad y acueducto en Colombia. Este artículo, además de reseñar dichos cambios, evalúa a través de un contrafactual cómo hubiese sido la evoluc...
Article
Spanish Abstract: El desarrollo de estrategias comerciales para realizar ventas cruzadas efectivas de servicios pensionales, puede ser uno de los retos más grandes de los fondos de pensiones. Se utilizó la base de datos de los afiliados a un fondo de pensiones obligatorias colombiano para implementar varios modelos que describen la incidencia de 4...
Article
Full-text available
Spanish Abstract: En el presente trabajo se desarrolla un análisis de las propiedades de los modelos Multinomiales a través de distintos procesos de simulación; lo anterior se realizó asumiendo tanto el cumplimiento de los supuestos subyacentes de los mecanismos de estimación como el incumplimiento de los mismos. Igualmente se analizó el comportami...
Article
This paper uses count and binary data models with an endogenous dummy variable, and propensity score matching to evaluate the effect of the subsidized health care program in Medellin (Colombia). The subsidized program, which primarily covers poor people, is found to have neither a significant impact on the use of preventive medical care nor hospita...
Article
Spanish Abstract: En este trabajo se utilizan los resultados obtenidos por los estudiantes en las áreas de matemáticas y lenguaje de las pruebas ICFES Saber 11º del segundo semestre de 2009, como medio para identificar los determinantes del rendimiento académico en Colombia. Para ello, se utiliza el modelo Logit Ordenado Generalizado. Los resultado...
Article
Spanish Abstract: El presente trabajo utiliza una Aproximación Lineal del Modelo Casi Ideal de Demanda (Linear Approximation/Almost Ideal Demand System) para examinar los gastos de los colombianos en la canasta básica, y estimar sus respectivas elasticidades precio y gasto, a partir de datos de series de tiempo para Colombia en el período de 1968-2...
Article
Full-text available
En este trabajo se presentan los resultados de una investigación empírica sobre los cambios en la posición de mercado de las empresas colombianas, según la matriz crecimiento-participación desarrollada por la firma Boston Consulting Group. Para ello se utilizan datos de la Superintendencia de Sociedades de Colombia y se aplican modelos logit multin...
Article
Spanish Abstract: La formacion y consolidacion de empresas constituye un elemento clave para lograr la transformacion social y economica de Colombia. Muestra de esta hipotesis, son el creciente numero de trabajos academicos y politicas encaminadas a fomentar la actividad emprendedora en el pais y sus regiones. Por tanto, se quiere contrastar lo obs...
Article
We develop and estimate a full information maximum likelihood ordered categorical response model with endogenous switching. Simulation exercises show that estimated parameters are unbias and consistent. And application to Internet access indicates that there are selection and moral hazard.
Article
This paper uses count and binary data models with endogenous switching, and propensity score matching to evaluate the effect of the subsidized health care program in Medellin (Colombia). The subsidized program, which primarily covers poor people, is found to have a negative association with the use of preventive medical care, but no significant imp...
Article
Full-text available
This work uses the results from the mathematics and language areas achieved by students in the 2009 second semester ICFES Saber 11° test to identify the academic performance determinants in Colombia. The Generalized Odered Logit model is used. The results show the relevance of socio-economical variables have in performance on both areas. In particu...
Article
Spanish Abstract: En este artículo se realiza una caracterización cuantitativa de la demanda de cupos universitarios por parte de bachilleres egresados de ciudades intermedias. Esto se realiza a través de modelos de elección discreta. Específicamente se encuentra que el número de programas ofrecidos aumenta la probabilidad de selección de las unive...
Article
Full-text available
En este artículo se contrasta empíricamente la validez del enfoque monetario de precios rígidos para la determinación de la tasa de cambio en la economía colombiana para el período 1995-2006 a través de la técnica econométrica de cointegración. Se encuentra que las variables relevantes en el modelo forman una relación estable de largo plazo, y que...
Article
Full-text available
Este artículo analiza diversas metodologías para la modelación de la volatilidad de la tasa de interés a corto plazo. Específicamente se analizarán los resultados que se obtienen a través de la especificación CKLS, heterocedasticidad condicio-nada y mixta. Los hechos estilizados enseñan que la mejor especificación para describir el proceso generado...
Article
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El presente artículo desarrolla las estimaciones econométricas de la tasa subjetiva de descuento y el parámetro de aversión al riesgo para la economía colombiana. El período de análisis es 1971- 2003 y la forma estructural del modelo son establecidas por el CCAPM. Se encuentra que el agente representativo se caracteriza por ser amante al riesgo e i...
Article
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Se analiza el cumplimiento de la hipótesis de Paridad Descubierta de Intereses entre Colombia y Estados Unidos para el período 2000-2005 mediante la técnica econométrica de cointegración. Específicamente se aplica la metodología desarrollada por Engle y Granger (1987) y la implementada por Johansen (1988). La evidencia empírica enseña que bajo las...
Article
Full-text available
In this paper is analyzed the macroeconomic effects associated with increases in the capital tax rate and labor tax rate under a Neoclassical model with elastic labor supply and positive externalities due to government's spending. It is found that these policies reduce the production, the investment and the labor supply; however, the effects over t...
Article
Full-text available
Se desarrolla el marco teorico implicito en la restricción presupuestaria intertemporal del gobierno. A partir de este se realizan una serie de simulaciones sobre el problema de sostenibilidad de la deuda publica, y los sacrificios fiscales necesarios para juzgar el actual nivel de endeudamiento sostenible. Se observa que Colombia ubicada en el con...
Article
Full-text available
En el presente escrito se presenta un aporte académico con miras a fortalecer el acercamiento a la teoría del crecimiento económico dada su relevancia a nivel teórico y práctico. En primera instancia se desarrollan algunas ideas fundamentales de la teoría del crecimiento económico, para luego tomar específicamente el modelo de crecimiento desarroll...