Unnatural Monopolies in Local Telephone
通过分析本地交换运营商的成本数据，发现成本函数不具有次可加性，表明打破现有垄断的收益大于效率损失，支持本地电话市场引入竞争。
We attempt to overcome the serious data problems of past telecommunications cost studies by focusing on local exchange carriers (LECs). With enough degrees offreedom to yield precise estimates, our global subadditivity tests show that the cost function is definitely not subadditive. The results suggest that the benefits to breaking up the monopoly outputs of existing LECs substantially outweigh the potential losses in efficiency. They also support permitting entry and increasing competition in local exchange markets. Furthermore, given the competitive nature of long distance service, it is doubtful that the predivestiture Bell System was a natural monopoly.