Specification and Testing of Models Estimated by Quadrature

This paper proposes a test to check the specification of models with unobserved individual effects integrated out by quadrature and also a simple way of increasing the flexibility of this type of model. The results of a Monte Carlo study and an application using a well-known data set illustrate the finite sample properties of the proposed methods and their implementation in practice.

Further simulation evidence on the performance of the Poisson pseudo-maximum likelihood estimator

We extend the simulation results given in Santos Silva and Tenreyro (2006, �The log of gravity,� The Review of Economics and Statistics, 88, 641-658) by considering data generated as a finite mixture of gamma variates. Data generated in this way can naturally have a large proportion of zeros and is fully compatible with constant elasticity models such as the gravity equation. Our results confirm that the Poisson pseudo maximum likelihood estimator is generally well behaved.

A cautionary note on tests for overidentifying restrictions

Tests of overidentifying restrictions are widely used in practice. However, there is often confusion about the nature of their null hypothesis and about the interpretation of their outcome. In this note we argue that these tests give little information on whether the instruments are correlated with the errors of the underlaying economic model and on whether they identify parameters of interest.

Hedonic Prices Indexes for New Passenger Cars in Portugal (1997- 2001)

This paper evaluates the effects of quality change on the price index for new passenger cars in Portugal for the years 1997-2001. Hedonic regression models are studied, giving particular emphasis to the relation between the form of the price index and the specification of the hedonic equation and estimation method used. It is argued that when log-linear hedonic functions are used the effects of quality change should be evaluated using a method akin to the Oaxaca decomposition (Oaxaca R., 1973, "Male-Female Wage Differentials in Urban Labor Markets", International Economic Review, 14, 693-709), rather than using the traditional dummy variables method. The results of the empirical part of the paper indicate that the CPI component corresponding to the sales of new passenger cars may have been overestimated by as much as 2.2 percentage points per year. This corresponds to an overestimation of the overall CPI by about 0.15 percentage points per year. As a by- product of this analysis it is also possible to conclude that the quality of new cars sold in Portugal increased on average 4.8 percent per year during this period.CPI bias; Heteroskedasticity; Oaxaca decomposition.

The Log of Gravity at 15

We review the contribution of “The Log of Gravity” (Santos Silva and Tenreyro, Rev Econ Stat 88:641–658, 2006), summarize the main results in the ensuing literature, and provide a brief review of the state-of-the-art in the estimation of gravity equations and other constant-elasticity models

Machine learning in international trade research - evaluating the impact of trade agreements

Modern trade agreements contain a large number of provisions in addition to tariff reductions, in areas as diverse as services trade, competition policy, trade-related investment measures, or public procurement. Existing research has struggled with overfitting and severe multicollinearity problems when trying to estimate the effects of these provisions on trade flows. Building on recent developments in the machine learning and variable selection literature, this paper proposes data-driven methods for selecting the most important provisions and quantifying their impact on trade flows, without the need of making ad hoc assumptions on how to aggregate individual provisions. The analysis finds that provisions related to antidumping, competition policy, technical barriers to trade, and trade facilitation are associated with enhancing the trade-increasing effect of trade agreements

Localization System for Optimization of Picking in a Manual Warehouse

Inbound logistics assumes increasing importance in retail operations, because there are usually hidden inefficiencies that contribute to higher labour costs and more time spent in the usual procedures in warehouses. The work developed was carried out in a manual warehouse of a retail company, with the main goal being the optimization of picking tasks and the improvement of the warehouse operations, as well as stock management. The solution is based on the development and implementation of a localization system, to reduce one of the most time-consuming components of picking, the search time for products in the warehouse. This application led to a reduction of this unproductive time by 93% to 100%, meaning the complete elimination of this component, which led to an optimization of the picking activity, by increasing the warehouse preparation capacity by 63%. Apart from the software upgrade, the operators now use Personal Digital Assistants to perform and validate the picking of items, increasing the accuracy of picking and the traceability of stock.info:eu-repo/semantics/publishedVersio

Significance Of Assessment Experiences During Initial Teacher Training In Physical Education

This study investigates how students in the final semester of their teacher training program (licensure) at the Center of Physical Education and Sports (CEFD), Espírito Santo Federal University, Brazil, (re)interpret their assessment experiences, an integral component of their teacher training. It employs the narrative as a theoretical and methodological perspective, and it utilizes student portfolios, as well as focus groups and semi-structured individual interviews as inputs for data generation. Ten students in their eighth, or final, semester participated in this study. These were the total respondents to a "call for volunteers" among the 2014 graduating class. The results suggest that the students believe the assessment processes of their teaching practices in physical education are disjointed. They feel that the disciplines that allow them to review their own performance during teacher training are more efficient and play a stronger role in their education.221627