A Strong Test of the von Liebig Hypothesis

An implication of the von Liebig hypothesis is that crop-production functions have right-angle isoquants. This article presents a nonparametric estimation of right-angle isoquant production functions. It then describes a new test for right-angle isoquants. The procedures are used to test experimental data on corn and wheat.     

Temporal and spatial modelling of tropical deforestation: a survival analysis linking satellite and household survey data

We estimate a spatially explicit model of the forest clearance process among smallholder farmers in an agricultural frontier of southern Mexico. Our analysis takes as its point of departure a simple utility‐maximising model that suggests many possible determinants of deforestation in an economic environment characterised by missing or thin markets. Hypotheses from the model are tested on a data set that combines a time series of satellite imagery with data collected from a survey of farm households whose agricultural plots were geo‐referenced using a global positioning system (GPS). We implement a survival analysis to identify the effect of household level explanatory variables on the probability of deforestation. This approach allows us to introduce a measure of the time until clearance as a covariate, thereby affording a control for the effect of potentially important explanatory variables that vary through time but are not directly observable. In addition to identifying several variables relevant for policy analysis, including household demographics, proximity to roads, and government provision of agricultural support, model results suggest that the deforestation process is characterised by non‐linear duration dependence, with the probability of forest clearance first decreasing and then increasing with the passage of time.     

Deforestation and land use change: sparse data environments

Understanding determinants of land use in developing countries has become a priority for researchers and policy makers with a wide range of interests. For the vast majority of these land use issues, the location of change is as important as its magnitude. This overview paper highlights new economic approaches to modeling land use determinants that combine non‐traditional data sources with novel economic models and econometric techniques. A key feature is that location is central to the analysis. All data elements include an explicit location attribute, estimation techniques include the potential for complications from spatial effects, and results are location‐specific. The paper reviews the theory underlying these models. Since this paper is intended to provide the potential new researcher with an introduction to the challenges of this analysis, we present an overview of how remotely‐sensed data are collected and processed, describe key GIS concepts and identify sources of data for this type of econometric analysis. Finally, selected papers using these techniques are reviewed.     

Do project managers' leadership competencies contribute to project success?

This article explores the following hypothesis: There is a statistically significant relationship between a project manager's leadership competencies and project success. Two proven questionnaires, the leadership dimensions questionnaire (LDQ) and the project success questionnaire (PSQ), were used to gather data from 52 project managers and project sponsors from a financial services company in the United Kingdom. The results from the LDQ and PSQ are presented in this article. A factor analysis of PSQ revealed three independent factors: usability, project delivery, and value of output to clients. The last factor is not related to project leadership or management, so the article concentrates on correlations between the other two factors and project leadership. Eight separate leadership dimensions were found to be statistically significantly related to performance, so the hypothesis was largely supported. Identifying such relationships provides managers with guidance on possible selection and project improvement models, whereby increased capability in leadership dimensions can lead to increased success in project management.     

Two-Stage Determinants of the Organic Food Retailing Landscape: The Case of Manhattan,New York

Retail sales of organic food products have been increasing faster than any other category of food and have penetrated mainstream retail grocery outlets. The majority of the literature on organic markets explores the socioeconomic characteristics of consumers, linking these traits to the probability of buying organic food, and it suggests that access to organic food is an important but overlooked factor in such studies. More recently, research focusing on food retailer marketing strategies for organic food finds that traditional strategies such as price promotions are largely unsuccessful with increasing sales for the organic food consumer. This article focuses on the retailer decision to offer organic food for sale. We model the decision as a two-stage process, where the retailer’s first decision is whether to sell organic food, and the second decision determines how many different organic products to offer for sale. In doing so, by using data collected in stores, we assess the organic food retail landscape in Manhattan, NY. We find that the decision to offer organic food for sale depends on the neighborhood socioeconomic characteristics, and the amount of organic food offered for sale depends on the size of the store.