基于Translog生产函数的北京市西瓜最优种植规模研究

农业适度规模经营是未来农业的发展方向,本文以规模经济理论为基础,通过建立Translog生产函数模型和DEA包络分析法,最终得出以农户为经营主体的北京市西瓜最优种植规模为6670m2(10亩)。除此之外,研究还发现种植户年龄及文化程度对西瓜种植具有显著影响,但随着农村人口老龄化日趋严峻,培养新型职业农民可以衔接西瓜种植的"断层"。     

Inter-regional comparisons of production technology in Canada's timber harvesting industries

Enhanced productivity in the logging industry is one of the key factors that determine the competitiveness of the forest products sector. Policy measures to improve efficiency must therefore start at the timber harvesting stage. This study analyzed and compared the production technologies in the timber harvesting industries of British Columbia (B.C.), Ontario, and Quebec, which are Canada's largest timber producing provinces. The study used annual data of log output and four inputs: labour, capital, energy, and materials from 1961 to 1999. Six models, encompassing different restrictions on the long-run translog cost function, were applied to each industry to determine the best technology for that industry. The cost function that best described each industry's technology was used to estimate own- and cross-price elasticities, input substitution elasticities, scale effects, technological change and bias, and total factor productivity. The production technologies of B.C. and Quebec were best described by homothetic, linearly homogeneous functions, while that of Ontario was found to be non-homothetic. Based on the Morishima elasticities of substitution, the results in general indicated inelastic substitution among all the four factor inputs. As a result the industries had limited options to make input adjustments with respect to changes in relative input prices; and hence required output levels were maintained at higher production costs. All three provincial industries exhibited biased technological changes, saving on capital and labour, and intensively using energy and materials. Labour and capital therefore recorded higher productivity than energy and materials over all provinces; consequently, efforts at improving the efficiency of the logging industries should focus on increasing the productivity of the latter inputs. Scale effects ranged from 2.17 in B.C. to 1.44 in Quebec implying that the timber harvesting industries appeared to have had the greatest potential for cost reduction through output expansion. In a competitive market structure, the strategic policy implication of these scale effects is that low-cost producers force high-cost industries out, leading to industrial concentration. The low levels of technological change in the timber harvesting industries observed in this study may reflect these industrial concentration problems. Policies that reduce the rental cost of capital, such an increase in investment tax credits and cuts in the corporate income tax rates have the potential to increase productivity and hence improve on the timber industry's competitive position.     

要素价格上涨对要素投入结构的影响研究——以花生生产为例

本文利用1998—2017年中国10个花生主产省(市)的面板数据,考察了初级生产要素价格上涨对我国花生生产要素投入结构的影响,进一步测算了要素之间的影子替代弹性,并分析了替代弹性的地区差异。本文对诱致性技术变迁理论进行了验证和拓展,研究发现:1)初级生产要素价格上涨和要素相对价格的提高对机械、化肥这两种要素投入均有显著的正向推动作用。化肥可以成为劳动的替代要素,土地要素与农业机械要素之间呈现伴随关系。2)劳动力与机械、劳动力与化肥、土地与化肥之间均存在明显的替代关系,土地与机械之间存在明显的互补关系。受地形条件的约束,劳动力与机械的替代弹性存在地区差异。因此,建议通过代耕代种、土地托管等多种形式的专业化服务促进土地适度规模经营,将农机农艺融合较为成熟的技术模式,作为农业农村部主推技术在花生主产区逐步推广,积极推广缓控释肥等新型肥料和分层施肥等新型节肥技术。     

Empirical specification of cost reductions associated with accumulated knowledge in the Swedish kraft paper industry

This paper presents an alternative approach in estimating the effect that technological knowledge has on the cost structure facing individual firms. The suggested method is applied to the Swedish kraft paper industry and relies on a comprehensive dataset for eight individual integrated kraft paper mills. The developed model is based on a two-step process. Step one, the estimation of a pure cost reduction index is derived using a flexible variable cost function which is utilising mill-specific dummy variables. In addition, this approach allows for an estimation of the pure unit cost reduction index that is devoid of scale and price effects which, if not dealt with can produce spurious results when estimating learning effects. Step two, is the estimation of a two factor dynamic learning curve model (2FDLC) using the estimated pure unit cost reduction index as dependent variable. The results suggest that the Swedish kraft paper industry has relatively little to gain in terms of cost reduction through a further technological learning. However, the method performed well, producing intuitive and statistically significant estimates indicating its usefulness in further analyses.     

Technical efficiency analysis of milkfish (Chanos chanos) production in Taiwan—an application of the stochastic frontier production function

Milkfish has been farmed in Taiwan for over 300 years. Faced with limited land resources, a labor shortage, decreasing demand, and growth of imported fisheries products, the industry is looking at the problem of how to maintain a sustainable and efficient production. This study specifies a stochastic production frontier function to estimate potential milkfish farm output and efficiency by using 1997–1999 data from a survey of 433 aquaculture milkfish farms. Both Translog and Cobb–Douglas frontier production models are estimated using the maximum likelihood estimation method. Empirical results show that the Translog stochastic production function model fits the data better and that milkfish farming in Taiwan exhibits diminishing returns to scale. We also compare estimated maximum potential milkfish production per hectare under various pond conditions to provide managers with information about how to boost efficiency. In addition, this study estimates substitution elasticities and complementarity of input factors for milkfish farms to provide helpful information for milkfish farmers on how to reallocate input resources and help raise milkfish productivity through improvements in technical efficiency.     

南疆地区气温变化及其对红枣产量的影响

通过分析南疆阿克苏、和田、喀什三地区1990~2011年内年平均温度、红枣各生育时期均温变化趋势,研究了温度对红枣产量的影响及对红枣产量变化的贡献情况。22年内南疆三地区年均温及红枣各生育时期均温均呈上升趋势,全年均温、萌芽开花期均温和果实膨大成熟期均温与红枣产量呈显著正相关,表明温度上升是提高红枣产量的重要原因。随机效应模型实证分析表明,南疆三地区温度变化对红枣产量变化的贡献率为7.54%,年温度每升高1℃,红枣产量提高9%~11.7%。     

基于生产函数理论的我国公路运输行业研究

利用Eviews软件,通过最小二乘法(OLS)回归确定了1995～2004年我国公路运输行业的生产函数,随后对此行业内资本和劳动投入进行了经济学分析,最后提出了今后几年合理配置公路运输业资源的建议.