【摘要】 随着全球化进程的推进,国际农业和食品体系经历着重大的变革。这种变革包括从自给自足到商品化生产,从沿街为市到现代零售业态,从食物短缺到饮食多样化,从食不裹腹到注重营养健康等诸多方面。然而与新兴的零售业态以及人们对农产品质量安全日益走高的诉求不相匹配的是分散高耗的农产品生产体系与繁杂低效的农产品流通体系。高质量需求与低质量供给造成了部分农产品的数量型结构性过剩。从生产率低下、半自给自足向生产率提高、商品化生产为主的转变,正是半个世纪甚至更长时间以来农业经济乃至整个经济发展的核心内容,可谓“农业的转型”。我国三十年的农村改革极大地解放了生产力,市场体制改革成效显著,但不容争辩的事实是我国的小农户仍然面临低端农产品的卖难问题。农产品生产者进入市场时面临的诸多难题当中最为突出的问题之一便是高昂的交易费用,这是一组伴随着交易的产生而发生的部分可观测和部分不可观测的费用。理论界对于交易费用的测量历来存在争议,微观领域市场交易的交易费用抑或是宏观领域体制运行的交易费用都存在不同的衡量方法。庆幸的是,国际国内学界对农业和食品供应链的发展给予了热切的关注。新制度经济学与信息经济学就交易费用与契约的关系做出了创造性且影响深远的阐释。理论上的突破也为经验研究提供了基本依据。就研究定位而言:首先,本文定位于经验研究,立足于细致访谈基础上构建的详实的数据库,运用经典数量模型的研究结论和计量方法对理论假说进行验证;其次,本文聚焦于一种产品,即以河北省和浙江省的小农户梨果产销为例进行研究;再次,本文主要关注的问题包括:梨果行业市场流通渠道如何?有哪些可供农户选择的契约模式?选择不同契约模式的农户生产和销售两个阶段的效率如何?假定交易费用的存在影响了不同契约模式的效率,如何构建指标体系考察小农户销售农产品时的市场型交易费用?交易费用是影响农户选择不同契约模式的重要因素这一假说是否成立?特定的契约安排是否能起到节省交易费用的目的?本研究的目的在于采用调研数据对理论界关于交易费用与农户契约选择关系的观点在中国的环境下进行经验论证,并指导我国转型经济中分散的小农户连接大市场的实践工作。本文共8章,章节的安排概述如下:第一章为绪论。主要任务在于交待本研究开展的现实背景和理论基础并引申出研究问题,阐述本研究的目的,界定本研究的基本概念,确立本研究的思路,陈述本研究可能的创新之处等。第二章为理论研究的文献综述。主要回顾交易费用经济学和契约选择理论的经典学说,并分析已有的研究框架可供改进之处。第三章为经验研究的文献综述。包括国内外关于交易费用测量的研究评述,重点概括了国内外农业经济领域关于交易费用与契约选择方面的经验研究成果。第四章为本研究的实证分析框架和研究设计的介绍。包括实证框架的构建,以及本研究数据收集的详细过程,包括样本区域的确定、抽样方法、问卷结构和数据采集过程的描述。第五章为梨果流通渠道与契约模式研究。包括我国及发达国家和地区水果流通体制改革的回顾,全国及样本省区梨果产业的概况,重点运用价值链分析工具对河北省和浙江省的梨果产业的价值链进行了系统的剖析,详细分析梨果生产和销售相关阶段的成本构成、增值比例和利润分配。在此基础上,总结可供梨农选择的契约模式的类型,并构建了两阶段梨果价值链模型以及运用数据包络分析方法(DEA)评价了不同契约模式的技术效率。第六章为理论假说的检验。本文提出的基本假说是交易费用是影响农户选择不同契约模式的重要因素,本部分将对此假说进行验证。本部分首先引入了本领域截止目前最为成熟的一个数理模型,其次详细地总结了已有研究在测度交易费用时采用的各类指标,在分析其利弊之后,提出了适合本研究所考察的梨果销售的交易费用衡量指标体系。计量检验方面本研究总结了本领域研究中前人使用过的计量模型,并尝试使用以往研究尚未采用的Multinomial Logit模型进行估计,验证交易费用是影响农户选择不同契约模式的重要因素这一基本假说是否成立。第七章为交易费用与契约选择的案例研究。在验证了交易费用是否是影响农户选择不同契约模式的重要因素后,本部分转而分析特定的契约安排能否起到节省交易费用的作用。本部分运用案例分析方法,解剖浙江省杭州市余杭镇蜜梨专业合作社实施合同农业的案例,探讨农民专业合作社这一特定的制度安排所采用的正式契约模式对于交易费用的节省作用。第八章为研究结论、政策含义及研究展望。本部分将对研究的主要结论进行高度凝炼,并在此基础上提出相应的政策建议。论文的最后部分阐述了本研究有待进一步完善的地方和可供进一步研究的方向。本研究发现:第一,梨作为一种传统的大路水果,其价值链的构成表现出差异化趋势,传统与现代的契约模式并存于该产业。第二,处于梨果产业价值链源头的小农户从增值中获益不多,流通环节攫取了大量利润。第三,通过数据包络分析所测量的两阶段技术效率表明:不同契约模式的交易效率并不相同,效率由高到低的契约模式分别是集团购买模式、合作社销售模式、消费者购买模式、零售商购买模式和批发商购买模式。第四,交易费用是影响农户契约选择的重要因素,这一假说得到了初步的验证。第五,农民专业合作社的案例研究表明:农民专业合作社实施的合同农业对交易费用的节省起到了积极的作用。

　　【关键词】 交易费用； 契约； 经验研究； 价值链； 效率； 梨；

　　【Abstract】 With the rapid expansion of globalization,significant changes have taken place in international agriculture and food system,including changes from self-sufficient to commercial production,from roadside stalls to modern shopping malls,from food shortage to dietary diversification,from suffering hunger to paying attention to health. However,new retail system and high quality demand of food safety are not matched by corresponding producing and circulation systems.The gap between high-quality demand and low-quality supply of agricultural products led to structural surplus.The transition from low productivity,semi-subsistence agriculture to high productivity,commercialized agriculture has been a core theme of development and agricultural economics for half a century or more,which can be called as transition of agriculture.Three decades of rural reform in China has been greatly liberating the productive forces,and remarkable performances have been achieved owing to the market reform.However,an indisputable fact is that small farmers in China are still facing difficulties in market participation.One of the most difficult problems for market accessing of producers is high transaction cost,which occurred in transactions, partly to be observed.Measurement of transaction cost has always been controversial.Different methods have been adopted in transaction costs of micro-markets as well as running costs of system of macro-structure.Fortunately,both international and domestic scholars pay a keen attention to agriculture and food supply chain.Creative interpretations of the relationship between transaction costs and contract selection have been made with the development of New Institutional Economics and Information Economics. Breakthroughs in theories provide the fundamental basis for empirical research.In terms of positioning of the study:First of all,this paper located in the empirical studies,based on detailed database from face to face interviews,and verified the theoretical hypothesis by using a number of classical mathematical models and econometric models.Second,this paper focused on one single product, namely,pear industry in Hebei province and Zhejiang province.Third,the main concerns of this paper,including market structure of pear industry,available contracts for farm households,measurement of transaction costs,efficiency of different contracts in two stages of the production and marketing,whether or not transaction costs are important factors that affect choices of farmers,whether or not specific contractual arrangements would save certain kinds of transaction costs. The purpose of this study is to test and verify theoretical conclusions on relationship between transaction costs and contract selection by using survey data under the background of Chinese economy,and to provide implications for small farmer adapting changing market in such a transition economy.There are eight chapters in this paper,and arrangements of each chapter are summarized as follows:Chapter 1 is the preface.The main function of this chapter is to introduce the practical and theoretical background of this study,as well as research purpose, concepts definition,methodology and expecting innovations.Chapter 2 is a review of theoretical literatures.By recalling the major transaction cost economics and contract economics of the classical theory,this chapter summarized possible improvements of existing research framework.Chapter 3 is a review of empirical research literatures,including a commentary for measurement of transaction costs and a summary of research results of transaction costs and contract selection in the area of agricultural economy.Chapter 4 is an introduction for empirical research framework and experimental design,including framework building,details of data collection,i.e.the determination of the sample regions,sampling methods,questionnaire structure and a description of the process of data collection.Chapter 5 is the study of marketing channels of pear industry and summary of contract patterns.In this chapter,we recalled reform of fruit circulation system in both China and developed countries and regions,introduced general information of the pear industry in China and pilot provinces,analyzed supply chains of pear industry in Hebei province and Zhejiang province by using the tool of value chain analysis, including cost composition,value adding activities and profit distribution of each stage.At the end of this chapter,we summarized available contract patterns for pear growers and evaluated efficiency of each contract pattern by using the procedure of Data Envelopment Analysis.Chapter 6 is testing for the hypothesis.In this paper,the basic hypothesis is that transaction costs are important factors affecting contract choice of farm households. This section introduces the latest mathematical model in this field,followed by a detailed study of indicators of transaction costs measurement.After analyzing of advantages and disadvantages of previous studies,we proposed a system to fit the attributes of pear marketing.In terms of econometric models,this study carefully reviewed models used in previous studies,and tried to use Multinomial Logit Model to test the basic hypothesis and estimate the impact of transaction costs to contract selection.Chapter 7 is the case study of contract arrangement and transaction costs.After testing the research hypothesis,we turned around,to focus on the role of specific contractual arrangement for saving transaction costs.Case study methodology has been adopted in this chapter by taking the example of Pear Grower Cooperatives of Yuhang Township in Zhejiang Province.Chapter 8 is the last part of this dissertation.The function of this chapter is to summarize research conclusions,policy implications and research prospects.The main findings of this research are as follows:First,as a traditional fruit as pear,constitutions of value chain and available contract patterns of such industry are complicated.Second,small-scale farm households can hardly benefit from value adding.Intermediary organizations grabbed a substantial flow of profits.Third,results of DEA showed that different contract pattern has different transaction efficiency. From the highest to the lowest are group buyer contract,farmer cooperative contract, consumer contract,retailer contract and wholesaler contract.Fourth,transaction costs are important factors affecting contract selection of farm households.Fifth,the case demonstrated that implementation in contract farming of farmer cooperatives played a positive role to save transaction costs。

　　【Key words】 Transaction Costs； Contract； Empirical Study； Value Chain； Efficiency； Pear；