Cash cropping and food crop productivity: synergies or trade‐offs?

The case for promoting export‐oriented cash crops in Africa has generally been based on their direct potential contribution to agricultural productivity and small farmer incomes. A relatively neglected avenue of research concerns the synergistic effects that cash cropping can have on other household activities, including food production. The conventional view that cash crops compete with food crops for land and labour neglects the potential for cash crop schemes to make available inputs on credit, management training, and other resources that can contribute to food crop productivity, which might otherwise not be accessible to farmers if they did not participate in cash crop programs. This article builds on previous research by hypothesising key pathways by which cash crops may affect food crop activities and empirically measuring these effects using the case of cotton in Gokwe North District in Zimbabwe. Analysis is based on instrumental variable analysis of survey data on 430 rural households in 1996. Results indicate that—after controlling for household assets, education and locational differences—households engaging intensively in cotton production obtain higher grain yields than non‐cotton and marginal cotton producers. We also find evidence of regional spill‐over effects whereby commercialisation schemes induce second round investments in a particular area that provide benefits to all farmers in that region, regardless of whether they engage in that commercialisation scheme. The study suggests that the potential spill‐over benefits for food crops through participation in cash crop programs are important to consider in the development of strategies designed to intensify African food crop production.     

供应链网络均衡模型

本文试图提出一种供应链网络的均衡模型。在这个模型里将充分考虑决策者的决策与他们各自独立的行为,并推导出供应链网络模型结构均衡的条件。     

Complexity and the limits to learning

In this paper we look at the manner in which ideas coming from complexity science change our understanding of the cognitive powers of agents that is really necessary to explain the evolution of markets and of firms. The general ideas behind complex systems dynamics and evolution are presented and then two examples are treated in detail. The first in an evolutionary model of a market in which some new product is developed by competing firms and their “task” is to find a strategy in terms of quality and price that will be sustainable. This essentially requires agents/firms to discover mutually compatible strategies, and to create thereby sustainable market niches. The second example considers the internal structure of firms, in terms of their constituent working practices and skills. It demonstrates that it is precisely their ignorance of the consequences of adopting any particular practice that generates diversity in the emergent capabilities of firms, exploring the dimension of potential demand and therefore leading to a successful and sustainable business sector. The work supports the notion that the cognitive abilities that are involved are not about deduction and logic, as a traditional view of rationality might suggest, but are about the development and contraction of interpretive frameworks, which will be different for each player. The paper links these examples to a general recognition of the idea that complex, multi-agent systems evolve through successive “structural attractors”—multi-dimensional dynamical systems—with temporary structural stability. Because real systems contain both the structure and deviations from it, then there is a constant probing of structural stability and the possibility of qualitative change to a new structural attractor. This resembles the ideas in biological evolution related to “punctuated equilibria,” but it also links this to the idea of emergent and evolving networks of interaction, never of course near thermodynamic equilibrium.      

Multi-level and mixed-level <Emphasis Type="Italic">k</Emphasis>-circulant supersaturated designs

Supersaturated designs (SSDs) constitute an important class of fractional factorial designs that could be extremely useful in factor screening experiments. Most of the existing studies have focused on balanced designs. This paper provides a new lower bound for the \(E(f_{NOD})\)-optimality measure of SSDs with general run sizes. This bound is a generalization of existing bounds since it is applicable to both balanced and unbalanced designs. Optimal multi and mixed-level, balanced and nearly balanced SSDs are constructed by applying a k-circulant type methodology. Necessary and sufficient conditions are introduced for the generator vectors, in order to pre-ensure the optimality of the constructed k-circulant SSDs. The provided lower bounds were used to measure the efficiency of the generated designs. The presented methodology leads to a number of new families of improved SSDs, providing tools for directly constructing optimal or nearly-optimal k-circulant designs by just checking the corresponding generator vector.     

Regulating,joint bargaining,and the demise of precedent

Recent decades have seen a fundamental shift in the nature of economic regulation in the United States. Unauthorized by congress, and largely unnoted in legal and academic circles, regulatory agencies such as the Federal Communications Commission have changed the regulatory process by linking otherwise unrelated regulatory issues. Examples include tying merger approval to firm commitments to engage in conceptually unrelated build‐outs and other projects of political importance. This linking of issues has several effects, the most prominent being (a) tying regulatory issues changes the outcomes obtained, plausibly in predictable ways; (b) tying in some circumstances allows regulators to extend their authority to issues for which they have little or no legal authority; and (c) tied regulatory bargaining fails to produce valid legal precedent for firm decision making. We provide an analysis of these conclusions by examining the increasing use of consent decrees, voluntary merger commitments, and merger conditions by the Federal Communications Commission, referencing our discussion with a simple model of joint bargaining applicable to regulatory practice.     

The cointegrated vector autoregressive model with general deterministic terms

In the cointegrated vector autoregression (CVAR) literature, deterministic terms have until now been analyzed on a case-by-case, or as-needed basis. We give a comprehensive unified treatment of deterministic terms in the additive model $X_t=\gamma Z_t+Y_t$, where $Z_t$ belongs to a large class of deterministic regressors and $Y_t$ is a zero-mean CVAR. We suggest an extended model that can be estimated by reduced rank regression, and give a condition for when the additive and extended models are asymptotically equivalent, as well as an algorithm for deriving the additive model parameters from the extended model parameters. We derive asymptotic properties of the maximum likelihood estimators and discuss tests for rank and tests on the deterministic terms. In particular, we give conditions under which the estimators are asymptotically (mixed) Gaussian, such that associated tests are ${\chi }^2$-distributed.     

The process of entrepreneurial action at the base of the pyramid in developing countries: a case of vegetable farmers in Benin

The assumption that entrepreneurship is a critical factor in expanding employment, creating wealth and contributing to poverty alleviation at the base of the pyramid (BoP) in developing countries has led to the development of many initiatives to strengthen the entrepreneurial activities of poor people. Despite the fact that entrepreneurship is seen as a strategy in combatting poverty, the process that leads to entrepreneurial action in a BoP context is still unclear. In this paper, we illustrate the possibilities a multi-layered perspective offers to understand the complexity of entrepreneurship in poverty settings. Based on five focus group discussions and 36 in-depth interviews with vegetable farmers in Benin, we examined the entrepreneurship of poor people. We learned that entrepreneurial action is the nexus of individual and exogenous factors in complex relationships. Based on this, we elaborate on the characteristics of the process model of entrepreneurial action. We provide a process-based view of entrepreneurship at the BoP, suggesting a need for consistency between individual, behavioural strategies and contextual elements. We discuss the implications of our findings for BoP practice and provide a framing perspective that we hope will encourage a greater focus on the complexity of entrepreneurship phenomenon.     

Do retail mergers affect competition? Evidence from grocery retailing

This study estimates the price effects of horizontal mergers in the U.S. grocery retailing industry. We examine fourteen regions affected by mergers, including mergers in highly concentrated and relatively unconcentrated markets. We identify price effects by comparing markets affected by mergers to unaffected markets using difference‐in‐difference estimation with three different comparison groups, propensity score weights, and by using the synthetic control method. Our results are robust to the choice of control group and estimation technique. We find that mergers in highly concentrated markets are most frequently associated with price increases, and mergers in less concentrated markets are most often associated with price decreases.     

What are the antecedents of women’s entrepreneurial orientation?

This study seeks to identify the antecedents of women’s entrepreneurial orientation (EO) and exploring what possible relationships that may exist between them. The research focuses on women entrepreneurs and non-entrepreneurs in a quantitative perspective whose methodology consisted of the collection of primary data through a survey distributed to women in Portugal. After structural equation modelling was applied, the results suggested that recognition of opportunities influences EO. This influence is expressed both directly and indirectly through training in management and entrepreneurial skills. These findings led to the conclusion that policies promoting training for community members, in general, need to be rethought and policies need to emphasise training in management that enhances entrepreneurial skills, thereby increasing the proliferation of entrepreneurship. Entrepreneurship education and training should be promoted from basic education onwards in order to develop entrepreneurial skills from an early age. Prior to this study, the relationships between opportunity recognition, management training and entrepreneurial skills have never been studied in relation to women.