本文採用「契約理論」研究途徑建立模型, 探討認證分級制度下農產品契作合約的設計。除了展現契作交易價格與最適分級認證標準的決定因素外，本模型亦能用以解釋契作合約隨「交易成本率」的下降而逐漸從市場消失的重要現象。

The study follows the "contract theory" to establish a model of a classification system for certification under the Lease of agricultural products for the design contract. In addition to show the optimal lease’s prices and classification standards for certification of the determining factors, an important phenomenon, this model can be used to interpret, Lease contract with a decline in transaction costs discount and gradually disappear from the market.

緒論....................................................................................................................................................................1
2 農產品分級認證契作交易............................................................................................................................5
2.1 產品生產與分級認證階段.........................................................................................................................6
2.2 中間商收購階段.........................................................................................................................................7
2.3 消費品市場階段: 中間商銷售與消費者需求...........................................................................................8
2.4 最適分級契作合約與最適分級標準.......................................................................................................10
2.4.1 分級契作合約之最適交易條件............................................................................................................10
2.4.2 認證制度最適分級標準之決定............................................................................................................13
3 生產者有直接銷售能力之產品分級契作合約...........................................................................................15
3.1 無中間商承包契作之消費市場均衡.......................................................................................................16
3.2 分級契作合約中間商之收購決策...........................................................................................................18
3.3 最適分級契作合約與最適分級標...........................................................................................................19
3.3.1 分級契作合約之最適交易條件...........................................................................................................19
3.3.2 認證制度最適分級標準之決定...........................................................................................................21
4 交易成本對契作交易之影響.....................................................................................................................23
4.1 生產者直接銷售與契作交易下勞動投入水準之比較..........................................................................23
4.2 中間商退出契作交易行列之交易成本條件.......................................................................................... 24
5 結論..............................................................................................................................................................27
參考文獻........................................................................................................................................................28
A 第二章之數學附錄.....................................................................................................................................29
A.1 求解最適契作合約之G1,G2,e 值..........................................................................................................29
A.2 命題1之證明................................................................................................................................,...........31
A.3 命題2之證明............................................................................................................................................32
A.3.1 以生產者角度求解最適分級標準X ................................................................................................... 32
A.3.2 以中間商角度求解最適分級標準.X ................................................................................................... 33
A.3.3 生產者與中間商聯合利益之角度求解最適分級標準X .................................................................... 35
A.4 中間商契作之經濟利潤...........................................................................................................................38
B 第三章之數學附錄......................................................................................................................................40
B.1 命題3.1之證明........................................................................................................................................ 40
B.2 命題3.2之證明........................................................................................................................................ 42
B.3 最適契作收購問題(3.15) 之求解過程.................................................................................................. 44
B.4 生產者與中間商聯合利益之角度求解最適分級標準X........................................................................ 46
C 第四章之數學附錄.....................................................................................................................................49
C.1 命題4之證明...........................................................................................................................................49
C.2 生產者與中間商之聯合利益恆不為負值 之證明................................................................................50
C.3 中間商退出契作交易條件之導引........................................................................................................ 51

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