Detecting collusion on highway procurement

Este trabajo se focaliza en el estudio de comportamientos cooperativos en mercados de subastas. Este artículo tiene dos objetivos principales. En primer lugar, desarrollar una metodología para detectar la presencia de cárteles usando el enfoque estructural. En segundo lugar, aplicar esta metodología a una base de datos de licitaciones para la construcción de carreteras en California. A través de la comparación de un modelo de competencia y un modelo de colusión se encuentra evidencia que sugiere que un subgrupo de firmas podría haber estado involucrado en un esquema colusivo.This paper proposes a procedure to detect collusion in asymmetric first-price procurement. The main objective is twofold. First, to provide a methodology to detect collusion using a structural approach, and second to apply the methodology to field data on procurement auctions for highway construction in California. I identify two different sets of firms as potential ring members. Relying on an exogenous number of bidders and the assumption that within each type bidders are symmetric, I find evidence supporting the collusive scheme, for the two mentioned sets of firms by comparing a model of competition and a model of collusion.Instituto de Investigaciones Económica

Econometrics of first price auctions: a survey of the theoretical and applied literature

Analizar mercados de subastas comprende un área activa de investigación, tanto en el plano teórico como empírico. Este trabajo contiene una revisión de la literatura relevante para realizar econometría de subastas desde la perspectiva del enfoque estructural. El enfoque estructural es un marco para analizar datos de subastas en el cual la teoría y la econometría están estrechamente vinculadas. Hay tres aspectos fundamentales para el enfoque estructural: (i) Existen restricciones testeables impuestas desde el modelo teórico sobre los datos? (ii) Es posible identificar a los elementos estructurales que caracterizan una subasta sin tener que recurrir a información paramétrica a priori? (iii) Que puede decirse sobre procedimientos implementables de estimación que no se basen en supuestos paramétricos? Esta recopilación muestra como la literatura sobre el enfoque estructural ha respondido a cada una de estas preguntas.The analysis of auctions is an active area of research for both theoretical and empirical economists. This paper provides an overview of the literature relevant to the econometrics of auctions from a structural approach perspective. The structural approach is a framework to analyze auction data in which theory and econometrics are closely related. There are three fundamental issues at the heart of the structural analysis: (i) Are there any testable restrictions imposed by the theoretic model on the data? (ii) Is it possible to identify the structural elements that characterize an auction without a priori parametric information? (iii) What can be said about feasible estimation procedures which do not rely on parametric assumptions?. This survey shows how the structural approach literature has answered each question.Instituto de Investigaciones Económica

The intertemporal relation between money and prices: evidence from Argentina

In this paper, we study the statistical relationship between money and prices in Argentina during the last quarter of the 20th century. We first look at the unit root characteristics of the series which suggest dividing the whole sample into two sub-samples: 1976 to 1989 and 1991 to 2001, as these sub-samples represent different exchange rate regimes. We then apply a filter similar to that of Lucas (1980) and find that correlations between changes in money and prices are highest when 12 month moving averages are used. In the early period, the correlation is almost one to one, while for the later period, the correlation is somewhat less and the relationship implies much smaller changes in prices for a given change in the money stock. Taking lags and leads in the moving averages of prices, we find very different temporal results for the two periods: changes in prices precede changes in money for the earlier period while changes in money precede changes in prices for the latter. These results are confirmed by Granger causality tests and VARs models. The main results of this paper are quite different from those found for developed countries. The reaction times we get are much shorter and the direction of causality (Granger) is also different.Departamento de Economí

Efectos distributivos de la educación: un enfoque de regresiones por cuantiles no condicionados

We use recent unconditional quantile regression methods (UQR) to study the distributive effects of education in Argentina. Standard methods usually focus on mean effects, or explore distributive effects by either making stringent modeling assumptions, and/or through counter- factual decompositions that require several temporal observations. An empirical case shows the flexibility and usefulness of UQR methods. Our application for the case of Argentina shows that education contributed positively to increased inequality in Argentina, mostly due to the effect of strongly heterogeneous effects of education on earnings.A través de la utilización del método de regresiones por cuantiles no condicionados (UQR) estudiamos los efectos distributivos de la educación en Argentina. Los métodos estándar usualmente se focalizan en los efectos sobre la media, o exploran efectos distributivos, ya sea imponiendo supuestos restrictivos para la modelización y/o a través de descomposiciones contra factuales que requieren una cantidad importante de observaciones temporales. Desde un punto de vista empírico se ha demostrado la flexibilidad y utilidad de los métodos UQR. Nuestra aplicación empírica para el caso de Argentina muestra que la educación ha contribuido positivamente a aumentar la desigualdad en Argentina. En mayor medida, esto se debe al gran efecto heterogéneo que tiene la educación sobre los ingresos.Facultad de Ciencias EconómicasCentro de Estudios Distributivos, Laborales y Sociale

The intertemporal relation between money and prices: evidence from Argentina

In this paper, we study the statistical relationship between money and prices in Argentina during the last quarter of the 20th century. We first look at the unit root characteristics of the series which suggest dividing the whole sample into two sub-samples: 1976 to 1989 and 1991 to 2001, as these sub-samples represent different exchange rate regimes. We then apply a filter similar to that of Lucas (1980) and find that correlations between changes in money and prices are highest when 12 month moving averages are used. In the early period, the correlation is almost one to one, while for the later period, the correlation is somewhat less and the relationship implies much smaller changes in prices for a given change in the money stock. Taking lags and leads in the moving averages of prices, we find very different temporal results for the two periods: changes in prices precede changes in money for the earlier period while changes in money precede changes in prices for the latter. These results are confirmed by Granger causality tests and VARs models. The main results of this paper are quite different from those found for developed countries. The reaction times we get are much shorter and the direction of causality (Granger) is also different.Departamento de Economí

The distributive effects of education: an unconditional quantile regression approach

En este trabajo utilizamos los más recientes métodos de regresión no condicionada por cuantiles (RNCQ) para estudiar los efectos distributivos de la educación en Argentina. Los métodos estándar se centran, por lo general, en efectos promedio o estudian los efectos distributivos ya sea haciendo uso de suposiciones estrictas al modelar y/o a través de descomposiciones contrafácticas que requieren varias observaciones temporales. La aplicación empírica en este trabajo muestra la flexibilidad y utilidad de los métodos de RNCQ. Nuestra aplicación para el caso de Argentina sugiere que la educación ha contribuido positivamente al aumento de la desigualdad, debido principalmente a efectos fuertemente heterogéneos de la educación sobre los ingresos.We use recent unconditional quantile regression methods (UQR) to study the dis- tributive eects of education in Argentina. Standard methods usually focus on mean eects, or explore distributive eects by either making stringent modeling assump- tions, and/or through counterfactual decompositions that require several temporal observations. An empirical case shows the exibility and usefulness of UQR methods. Our application for the case of Argentina shows that education contributed positively to increased inequality in Argentina, mostly due to the eect of strongly heterogeneous eects of education on earnings.Centro de Estudios Distributivos, Laborales y Sociales (CEDLAS

Ethnobotanical, micrographic and pharmacological features of plant-based weight-loss products sold in naturist stores in Mexico City: the need for better quality control

The consumption of dietary supplements and herbal mixtures to promote weight loss is a common practice in the West. This study was undertaken in Mexico City, surveying stores selling "natural products" at subway stations. The aims of this paper were as follows: to compile a record of plant products marketed as slimming aids and of retailer perceptions of these products; to review the pharmacological and ethnobotanical literature on the species declared; and to create an optical micrograph of a subset of products to verify the accuracy of the list of component plant species shown on the labels. We applied the techniques of observation, semi-structured interviews and free-listing at the retail stores. Results are presented for the 75 species recorded in the 41 weight-loss products surveyed, showing which plant parts are used, the geographical distribution of the species, pharmacological effects, dosage, route of administration and method of preparation, as well as ethnobotanical information derived from fieldwork. We discuss the values assigned to the species used. Microscopic analyses revealed that many of the plant ingredients declared were absent, highlighting the need for greater quality control and safety of these herbal remedies.Facultad de Ciencias Naturales y Muse

Ethnobotanical, micrographic and pharmacological features of plant-based weight-loss products sold in naturist stores in Mexico City: the need for better quality control

The consumption of dietary supplements and herbal mixtures to promote weight loss is a common practice in the West. This study was undertaken in Mexico City, surveying stores selling "natural products" at subway stations. The aims of this paper were as follows: to compile a record of plant products marketed as slimming aids and of retailer perceptions of these products; to review the pharmacological and ethnobotanical literature on the species declared; and to create an optical micrograph of a subset of products to verify the accuracy of the list of component plant species shown on the labels. We applied the techniques of observation, semi-structured interviews and free-listing at the retail stores. Results are presented for the 75 species recorded in the 41 weight-loss products surveyed, showing which plant parts are used, the geographical distribution of the species, pharmacological effects, dosage, route of administration and method of preparation, as well as ethnobotanical information derived from fieldwork. We discuss the values assigned to the species used. Microscopic analyses revealed that many of the plant ingredients declared were absent, highlighting the need for greater quality control and safety of these herbal remedies.Facultad de Ciencias Naturales y Muse

Efectos distributivos de la educación: un enfoque de regresiones por cuantiles no condicionados

We use recent unconditional quantile regression methods (UQR) to study the distributive effects of education in Argentina. Standard methods usually focus on mean effects, or explore distributive effects by either making stringent modeling assumptions, and/or through counter- factual decompositions that require several temporal observations. An empirical case shows the flexibility and usefulness of UQR methods. Our application for the case of Argentina shows that education contributed positively to increased inequality in Argentina, mostly due to the effect of strongly heterogeneous effects of education on earnings.A través de la utilización del método de regresiones por cuantiles no condicionados (UQR) estudiamos los efectos distributivos de la educación en Argentina. Los métodos estándar usualmente se focalizan en los efectos sobre la media, o exploran efectos distributivos, ya sea imponiendo supuestos restrictivos para la modelización y/o a través de descomposiciones contra factuales que requieren una cantidad importante de observaciones temporales. Desde un punto de vista empírico se ha demostrado la flexibilidad y utilidad de los métodos UQR. Nuestra aplicación empírica para el caso de Argentina muestra que la educación ha contribuido positivamente a aumentar la desigualdad en Argentina. En mayor medida, esto se debe al gran efecto heterogéneo que tiene la educación sobre los ingresos.Facultad de Ciencias EconómicasCentro de Estudios Distributivos, Laborales y Sociale

Genetic characterization of Callosciurus (Rodentia: Sciuridae) Asiatic squirrels introduced in Argentina

Squirrels have been traded in the pet market for several decades, and numerous species have established in the wild. The Asiatic species Callosciurus erythraeus and Callosciurus finlaysonii have been introduced into other parts of Asia, in Europe and South America. In this study, (1) we conducted a genetic characterization of C. erythraeus introduced into Argentina and compared them with native and introduced populations in Asia, and (2) we analyzed genetic variation among the four invasion foci in Argentina in order to corroborate that the pathway of invasion was a single introduction event in the country and subsequent translocations. We analyzed mitochondrial (cytochrome b, Cyt b; cytochrome oxidase c subunit I, COI and D-loop) and nuclear (recombination activating gene I, RAGI) DNA markers using the classical method (DNA barcoding gap analysis) and also the Automatic Barcode Gap Discovery method (ABGD). The markers D-loop, COI, and RAG1 indicated that the introduced squirrels from the different invasion foci formed a monophyletic group that, together with only one haplotype for the D-loop and COI markers, supported the hypothesis of one introduction event into Argentina followed by subsequent translocations. Unexpectedly, sequences from squirrels captured in Argentina were more related to C. finlaysonii than to C. erythraeus for D-loop and Cyt b markers. However, intraspecific variation among sequences of C. erythraeus belonging to different subspecies or collected in different regions was large and comparable with the distance to the sequences from Argentina. The ABGD method also indicated large genetic variability within C. erythraeus and close proximity between squirrels from Argentina and C. finlaysonii. The complex taxonomy of Callosciurus, as occurs with the sister species C. erythraeus and C. finlaysonii, requires a thorough systematic revision. A simultaneous analysis of diagnostic morphological characters and genetic markers is needed and will provide new insight regarding the worldwide invasion of Asiatic squirrels.Centro Regional de Estudios Genómico