Examining the relationship between farm size and productive efficiency: a Bayesian directional distance function approach

Achieving sustainable food security and increased farm income will depend on how efficient production systems are in converting available inputs to produce outputs. Using data from Malawi, we estimate a Bayesian directional technology distance function to examine the relationship between farm size and technical efficiency. Our results support the existence of an inverse relationship between farm size and productive efficiency, where small farms are more efficient than large farms. On average, farms exhibit inefficiency levels of 60%, suggesting that productivity could be improved substantially. Improving productive efficiency and food security will require farms to operate in ways where the size of cultivated area is matched by nonland production inputs such as labor, fertilizer, and improved seeds. The results highlight the need for policies that could incentivize farmers to adopt productivity‐enhancing technologies and, where possible, to allocate excess land to lease markets.     

A consistent model specification test with mixed discrete and continuous data

In this paper we propose a nonparametric kernel-based model specification test that can be used when the regression model contains both discrete and continuous regressors. We employ discrete variable kernel functions and we smooth both the discrete and continuous regressors using least squares cross-validation (CV) methods. The test statistic is shown to have an asymptotic normal null distribution. We also prove the validity of using the wild bootstrap method to approximate the null distribution of the test statistic, the bootstrap being our preferred method for obtaining the null distribution in practice. Simulations show that the proposed test has significant power advantages over conventional kernel tests which rely upon frequency-based nonparametric estimators that require sample splitting to handle the presence of discrete regressors.     

结构变化的节能潜力计算的方法论研究

本文介绍了几种计算节能的因素贡献份额的方法,通过分析指出了部门能源强度与技术贡献之间的差别。在定义明确后,经公式计算与分解处理的结果表明,中国在1995～2002年总能源强度下降中,结构节能贡献大约在60%以上; 2002年以后总能源强度呈上升趋势,这时的结构变化推动能源强度上升(对节能起负作用)。符合客观实际的结论应是,结构变化对能源强度变化的影响还是很大的。     

Are outsourcing and non-aeronautical revenues important drivers in the efficiency of Spanish airports?

This paper evaluates the influence of contracting out, or outsourcing, certain airport services and of commercial diversification strategy. Although most of the effort is being put towards applying non-parametric techniques in airport efficiency studies, we have chosen parametric methodology. We use a distance function, as it has known advantages. The findings show the positive contribution of outsourcing and non-aeronautical revenues on the efficiency of the Spanish airports' network.     

基于Visual Basic与Auto CAD的包装纸盒参数化设计系统开发

针对包装纸盒设计过程复杂及现有设计软件昂贵的现象,利用纸盒结构设计的一般方法和图形显示及输出的通用模式,基于Visuall Basic和AutoCAD平台,开发了参数化纸盒设计系统。该系统形成了在纸盒结构设计系统中进行设计及在AutoCAD中进行结构显示的新模式,符合现代纸盒设计工作流程,最终达到克服现有纸盒设计过程及软件的不足,提高设计效率,降低设计成本的目的。     

The pricing of basket-spread options

Since the pioneering paper of Black and Scholes was published in 1973, enormous research effort has been spent on finding a multi-asset variant of their closed-form option pricing formula. In this paper, we generalize the Kirk [Managing Energy Price Risk, 1995] approximate formula for pricing a two-asset spread option to the case of a multi-asset basket-spread option. All the advantageous properties of being simple, accurate and efficient are preserved. As the final formula retains the same functional form as the Black–Scholes formula, all the basket-spread option Greeks are also derived in closed form. Numerical examples demonstrate that the pricing and hedging errors are in general less than 1% relative to the benchmark results obtained by numerical integration or Monte Carlo simulation with 10 million paths. An implicit correction method is further applied to reduce the pricing errors by factors of up to 100. The correction is governed by an unknown parameter, whose optimal value is found by solving a non-linear equation. Owing to its simplicity, the computing time for simultaneous pricing and hedging of basket-spread option with 10 underlying assets or less is kept below 1 ms. When compared against the existing approximation methods, the proposed basket-spread option formula coupled with the implicit correction turns out to be one of the most robust and accurate methods.     

Frontier Production Functions and Technical Efficiency Measures

The concept of technical efficiency is central to measuring the firm performance. The measurement of technical efficiency has proved difficult and complex, and the literature provides a range of methodologies. This paper reviews the various methodologies for measuring technical efficiency and offers a comparison between established methods of measurements. The discussion is literary with less mathematical jargons and equations. The objective of this paper is not to be exhaustive, but to be up‐to‐date and to provide a significant discussion on some of the core methods of measuring technical efficiency.     

Modelling income distribution using the log Student’s t distribution: New evidence for European Union countries

Income distribution remains a crucial topic in economic analysis, among other reasons, due to the increase in inequality in recent years, as one of the effects of the Great Recession. In this context, proposing parametric models that represent the full distribution through a small number of parameters arouses great interest as an instrument for economic analysis. This paper studies the ability of log Student’s t distribution to model the size distribution of income due to its potential to reproduce the effect of a mode around low-incomes as well as its precision in capturing the degree of kurtosis of empirical distributions. These characteristics make the log-t an ideal analysis tool, for instance, for exploring the effects of anti-poverty policies. The model has been fitted to income data for the EU25 and for several years. The conclusion is that the log Student’s t distribution offers the best fit in the vast majority of cases.     

Parametric bootstrap tests for continuous and discrete distributions

Statistical procedures based on the estimated empirical process are well known for testing goodness of fit to parametric distribution families. These methods usually are not distribution free, so that the asymptotic critical values of test statistics depend on unknown parameters. This difficulty may be overcome by the utilization of parametric bootstrap procedures. The aim of this paper is to prove a weak approximation theorem for the bootstrapped estimated empirical process under very general conditions, which allow both the most important continuous and discrete distribution families, along with most parameter estimation methods. The emphasis is on families of discrete distributions, and simulation results for families of negative binomial distributions are also presented.     

Determinants of efficiency of vegetable production in smallholder farms: The case of Ethiopia

Improving production efficiency remains as a plausible means of increasing productivity when resource reallocation, and the creation and adoption of new technologies are limited. Technical, allocative and economic efficiencies are derived from a sample of smallholder vegetable farmers in Ethiopia using parametric and non-parametric methods. The results reveal that the two methods yield similar estimates and the existence of substantial inefficiencies in production as well as efficiency differentials among farmers. The analysis of the determinants of efficiency of vegetable production using regression models show that low asset ownership, illiteracy, large family size, inadequate extension contacts, small farm size, age, low off/non-farm income and high consumer spending are the major socio-economic factors causing inefficiency of vegetable production in the study areas. A comparison of the market-driven (vegetables) with the whole-farm (crops and livestock) production efficiency indicates that lower economic efficiency scores for the former might be related to the limited access to capital markets, high consumer spending, and large family size.