過去研究銀行廠商成本效率(包括規模與多元經濟)者,皆未考量廠商的經濟無效率(包括技術與配置無效率二種),簡稱x效率。換言之,這些研究者假設廠商已達效率邊界,在此效率邊界上衡量成本效率。如此,成本效率與x效率兩種因素相互混淆,使估計結果產生偏誤。本研究使用隨機成本邊界模型,同時將成本效率與x效率包含進來,使成本效率的估計結果不受x效率的影響。研究結果顯示,我國銀行廠商具有規模與多元經濟;若模型中不包含x效率,將會低估規模與多元經濟,其中以後者所受影響較大。
Most studies on the economies of scale and scope in banking assume no x-inefficiencies, that is, banks are always on their efficient frontier. This could confound scale and scope efficiencies with x-efficiencies. The current paper employs a stochastic frontier cost function incorporating technical and allocative inefficiencies as well as a system of share equations to estimate scale and scope efficiencies. Using data from Taiwan`s banking sector, evidence is found that the assumption of no x-inefficiencies results in underestimating scale and scope economies.