政府採購之良窳攸關國家公共建設、國民生計及大眾利益，因此，除應符合公平、公開之採購程序外，更應力謀於合理之價格條件下，提昇所擬採購標的之效用，以滿足機關達成符合最多數人之最大利益之需求目標。 歸納國內政府採購法所規範之決標原則，其競標精神不外於「合格最低標」及「最有利標」兩種，機關選擇決標方式，通常以產品之「效用」與「價格」為主要考量之因素，並應以高效用與低價格為最佳組合方案，惟在實務上兩者通常無法兼顧。 本研究藉由個體經濟學相關理論，並透過採購案件實例作專家問卷及資料分析，針對機關對採購標的之效用與價格滿意度進行分析，所建置之政府採購決標滿意度評估模型－「C.K.曲線」，為一條偏好相同之無異曲線，每一條相互平行之C.K.曲線，均分別代表一特定偏好之無異曲線，此特定偏好可由該曲線方程式之常數值定義之。 由C.K.曲線得知：（一）產品效用愈高，機關對產品之效用滿意度就愈大，但每增加一單位之滿意程度，效用滿意度之增加量有遞減之趨勢；（二）對產品效用滿意度愈高，對其價格不滿意度愈低，兩者呈現反向變動關係，具有替代性；（三）維持機關某最大特定偏好或主觀價值水準，產品之單位效用滿意度與單位價格不滿意度之比，為效用滿意度與價格不滿意度之替代率，具有遞減趨勢。 藉由本研究所建置之模型曲線，提供採購機關確立採購標的之價值目標，據以評估最佳之決標方式，同時對投標廠商參選標的效用與價格作合理之評價。 This paper establishes a model to identify the mechanism of selecting contractors by public sectors; and, by using indifference curve, to explain exchangeability between the most advantageous bid and the lowest bid. Literature reviews the concepts of procurement and economic discussions to support the procurement and consumer behaviors. With the viewpoint of consumer behavior, a model based on indifference curve theory is found utilizing mathematical hypotheses and construction. It is proved that a power function as well as an indifference curve, named Chen-Kuo curve, exists with satisfaction of statistical evaluation. Exchangeability between the most advantageous bid and the lowest bid is also provided to support the mechanism of a public sector’s contractor selection. The contribution provided by this paper to both practice and research is that a conceptual methodology is introduced to reasonably explain procurement behavior, and a solution is for contractor selection by a public sector.
