Applying cointegration and error correction to measure trade linkages: maize prices in the United States and Mexico

The impact of U.S.‐grown maize on Mexican markets is a subject of heated debate, and is complicated by limited substitution between white and yellow maize as well as regional price differences within Mexico. This article improves on previous analyses using a detailed data set of white maize prices reported weekly in 11 states across Mexico from 1998 through 2005. Using cointegration analysis and the error‐correction model, we find that prices between the United States and Mexico do not share a common long‐run relationship. Within Mexico, prices in Michoacán and Oaxaca are only weakly related with prices in neighboring states, whereas prices in Sinaloa and Jalisco exert considerable influence on prices elsewhere in Mexico. We conclude that, despite North American Free Trade Agreement (NAFTA), white maize prices in Mexico are determined by local conditions including particularly the degree of integration to other regions within Mexico.     

A volume and material handling cost based heuristic for designing cellular manufacturing cells

One of the major problems in a group technology or cellular manufacturing environment is the formation of part groups and machine cells. Because of the combinatorial nature of the cell formation problem, it is difficult to solve the problem optimally. Most of the procedures related to cell design in cellular manufacturing operate on the part-machine incidence matrix in an attempt to identify block diagonality. If complete block diagonality does not exist, the decision about cell configuration is left to the subjective judgement of the designer. These procedures are also generally based on part routing only, and do not consider part volume and material handling costs.In this paper we develop an integer programming model, as well as a heuristic to effectively assign machines to cells. In these procedures we consider component volumes, costs related to movement of components between and within cells, and penalty for not using all machines in a cell visited by a component. Since the integer programming formulation becomes large even for small problems, an efficient heuristic is developed to solve larger problems. The heuristic solutions to 180 randomly generated small problems were compared against the optimal solutions obtained by the integer programming model. The heuristic has been found to identify optimal solutions in all 180 cases.This heuristic is also compared to several well known algorithms on 900 larger test problems. These problems were generated to cover a wide range of environmental situations such as varying levels of block diagonality in the part-machine incidence matrix, and diversity in the component volumes and material handling costs. In 99% of the problems our heuristic generated solutions which are better or as good as the best solution obtained by other algorithms. Further, in situations where complete block diagonality in the part-machine incidence matrix did not exist, our heuristic produced even better results. Since the maximum number of iterations required in our heuristic is the number of machines in the problem, the heuristic is computationally efficient.     

Possible Applications of Survival Analysis in Franchising Research

Time is an important variable for retailers. The concepts of survival and duration, linked to this time variable, can be very interesting in franchising research. For instance, what are the determinants of the survival of a network or a store? Which elements decrease the period before franchising or internationalising a network? There is a well adapted but little-exploited methodology in this research area: survival analysis. Consequently, this methodological paper presents in detail survival analysis methodology before giving relevant examples of applications in the franchising field. Managerial implications of these kinds of research are given before the conclusion.     

Agriculture,transportation and the timing of urbanization: Global analysis at the grid cell level

This paper addresses the timing of a location’s historical transition from rural to urban activity. We test whether urbanization occurs sooner in places with higher agricultural potential and comparatively lower transport costs, using worldwide data that divide the earth’s surface at half-degree intervals into 62,290 cells. From an independent estimate of each cell’s rural and urban population history over the last 2,000 years, we identify the date at which each cell achieves various thresholds of urbanization. Controlling for unobserved heterogeneity across countries through fixed effects and using a variety of spatial econometric techniques, we find a robust association between earlier urbanization and agro-climatic suitability for cultivation, having seasonal frosts, better access to the ocean or navigable rivers, and lower elevation. These geographic correlations become smaller in magnitude as urbanization proceeds, and there is some variation in the effects across continents. Aggregating cells into countries, we show that an earlier urbanization date is associated with higher per capita income today.     

Does maternal employment affect child nutrition status? New evidence from Egypt

Even though maternal employment can increase family income, several studies suggest that it could have adverse consequences on children’s health. In this study, we use a nationally representative sample of 12,888 children, aged 0–5 years from Egypt to examine the impact of maternal employment on child nutritional indicators, namely: stunting, wasting, and being underweight and overweight. We adopted various estimation methods to control for observable and unobservable household characteristics in order to identify the causal effect of maternal employment. These different techniques include, propensity score matching (PSM), OLS regression with controlling for a wide range of individual characteristics, and an instrumental variable two-stage least squares (IV 2SLS) approach. Results of the PSM and OLS suggest that maternal employment is weakly associated with having a malnourished child. On the other hand, the IV 2SLS suggests a stronger and significant association between maternal employment and poor nutritional status among children.     

Bayesian hierarchical statistics for traffic safety modelling and forecasting

Abstract

Road traffic accidents (RTAs) represent a serious problem globally causing losses in many ways. Gulf Cooperation Council (GCC) countries have a high rate of RTAs compared to other high-income countries. In this study, a Bayesian hierarchical model was utilized for accident counts forecasting in Abu Dhabi, United Arab Emirates. This work will help traffic planners and decision makers to enhance road safety levels and decrease accident fatality rate. Accidents data along 5 years from 2008 to 2012 at 143 road sites in Abu Dhabi with 5,511 accidents were used. The proposed model considered a number of covariates; speed limit, type of road, number of lanes, type of area, weather, time, surface condition and seat belt usage. Five sites with the highest numbers of accidents were studied. Year 2012 was used to validate predictions. The model prediction accuracy was 72%.     

A review of traffic safety status in Abu Dhabi city,UAE (2008–2013)

Large numbers of traffic accidents were experienced on the road networks of Arab Gulf Countries including United Arab Emirates (UAE). This had resulted in enormous loss of lives and economy. This article through using Abu Dhabi city, UAE capital as a case study is aiming to understand the reasons behind such safety problem through analysing a large accidents data-set extending over the period from 2008 to 2013. The traffic accidents data-set was obtained from Abu Dhabi traffic police department records and covers wide range of accident's attributes. A wide spectrum of accident attributes was analysed in the paper including but not limited to the time of accident, accident location, type of accident, reasons behind the accident, driver characteristics, road conditions, and many other accident attributes. A specific reasoning for each of these attributes was given by authors. Furthermore, recommendations to enhance the safety levels were introduced.