結構—行為—績效學派經常利用產業內各廠商的平均利潤，作為衡量市場獨占力 量的指標。本項研究計畫嘗試利用理論與實例說明：過度倚賴全體廠商的平均利 潤推斷超額利潤，可能會導致錯誤的結論。基於Mill, Fawcett, Hobson 與Friedman 等傳統古典智慧的觀點，本項計畫將評估利用邊際廠商（也就是效率最低的廠商） 的獲利，作為衡量市場力量指標的可行性。
The SCP school prefers to use accounting data for the industry ‘average’ profit rate to measure market power. This project plans to demonstrate that over-reliance on average profit across all firms to infer excess profit might lead to incorrect inferences regarding market power. Based on the conventional wisdom of Mill, Fawcett, Hobson, and Friedman, this project will evaluate the feasibility of using the profit rate of the marginal firm (the least efficient firm) as an indicator to measure market power, rather than the industry average profit rate.
