本文以臺北市政府公共工程的發包資料為研究對象，獲得投標廠商數對工程決標價格影響為負向，支持傳統拍賣理論的預測。實證研究過程中的另一項發現為，公共工程的議價比價制度對工程決標價何有正向的影響。若進一步細究，則發現公營廠商參與承攬，對臺北市公共工程決標價格有提高的重要影響。 另外以監察院的報告資料為佐證，則證實公營廠商承攬公共工程價格偏高的傾向具有普遍性。若改以同一件工程做為不同發包制度的比較基礎時，則由本文搜集的七個工程為例，發覺工程發包由議價改為公開招標，平圾可為政府部門節省37％的成本支出。 以工程發生延誤的比例和工首發生延誤時間的長短兩項指標做為工程品質的衡量，研究的結果則顯現政府以高價格的議價方式發包工程，並不一定保證有高品質。顯示政府內部以議價方式，將工程發包予公營廠商的做法，實有大幅改進的必要。

　　　　　This paper examines the impact of auction systems on the prices of public constructions using relevant data from the Taipei city government. It is found that resolved prices of public constructions are negatively correlated with the number of firms that are qualified to enter the bid. Instead of open tendering, negotiation or selective tendering systems are often adopted to guarantee the quality of constructions. The two auction systems increase the prices of public constructions as well. Participation of public enterprises in the systems of negotiation or selective tendering is a common phenomenon. This raises the prices of public constructions further. A report written by the Control Yuan reveals the same evidence. Using data of seven public projects of this study, we discover that the expenditures of public constructions can decrease by as much as 37% when auction systems are changed from negotiation to o[en tendering. In addition, judging from the indices of both delaying percentages and delaying time periods, quality of public constructions cannot be certified by the auction systems of negotiation and selective tendering. Therefore, contracting with public enterprises for civic projects is highly questionable.