COMPETITION AND COST OVERRUNS IN PROCUREMENT*
研究了公共采购中为何初始设计投入不足，导致成本超支频发。通过两阶段模型发现，承包商横向差异化时，赞助商最优策略是少投入设计，从而引发成本超支，而竞争不足是根本原因。
Most cases of cost overruns in public procurement are related to important changes in the initial project design. This paper provides a rationale for the observed pattern in public procurement of underinvestment in design specification. We propose a two‐stage model in which the sponsor first decides how much to invest in design specification and auctions the project to horizontally differentiated contractors. After the contract has been awarded and implemented, the sponsor and contractor receive new information about the optimal project design and renegotiate the contract to accommodate changes in the initial project's design. We show that the sponsor's optimal strategy is to underinvest in design specification, which makes significant cost overruns likely. Since no such underinvestment occurs when contractors are not horizontally differentiated, cost overruns are seen to arise as a consequence of lack of competition in the procurement market.