私人边际成本

这就是经济学家们说的私人边际成本与社会净成本之间的差别。

That is what economists mean when they talk about the difference between marginal private cost and net social cost .

在存在负外部性的情况下，由所有银行机构承担的社会边际成本将超过由单个银行机构承担的私人边际成本，此时，银行机构相对过剩，金融市场无效率。

Under the condition , society marginal cost borne by all banks exceeds personal marginal cost bear by single bank , which brings on superfluous banks relatively and inefficient financial market .

由于技术创新产出的非独占性，创新者不能完全攫取创新的全部收益，从而基于边际私人收益等于边际成本决定的私人最优创新水平必然小于社会最优创新水平。

Because not all of the outputs of innovation belong to enterprises that do innovation , the amount of innovation when marginal private profit equals marginal cost must be less than that when marginal social profit equals marginal cost .