One criticism of Fogel's analysis is that it does not account for the externalities or "spill-over" effects of the railroads, which (if included) may have increased his estimate for social savings .
针对福格尔的分析的一种批评认为，他的分析没有考虑到外部差异因素或铁路的“满溢”效应（"spill-over" effects），而如果把这些都加上的话，就会增加他的关于社会节约方面的结算结果。