由於放款市場上先天存在顯著的資訊不對稱問題，一方面會出現好 的借款人從市場退卻的「逆選擇」問題；另方面則會誘引不好的借款人 拒絕正常履約的「道德危機」問題。因而，若銀行「普遍」對於企業的 徵信工作未能落實，則易發生「粗心放款者(careless lender)」，或因若干 銀行「特定」往來對象是經營不善企業，則易產生「壞的借款者」。然而， 是「粗心放款者」抑或「壞的借款者」使銀行經營效率低落，而好的借 款人是否能提升銀行效率？為本研究的主要目的與動機。本研究2006 年至2011 年間國內38 家銀行為研究對象，首先利用主成份分析法來找 出銀行授信對象好的借款人與壞的借款人的關鍵變數，其次根據Battese and Coelli (1995)之隨機邊界法(stochastic frontier approach, SFA)，進行一 階段同時估計成本函數及無效率模型，無效率的變數包括：好的借款人 與壞的借款人、貨幣成長率、逾期放款比率、呆帳覆蓋率。本國銀行向 以放款業務為其主要獲利來源，而到底是「粗心放款者」抑或「壞的借 款者」，是驅使銀行經營效率降低的主因呢？希望透過本研究可以獲得具 體結論並提供銀行相關的授信建議。

For congenital significant asymmetry information existing in the loan market, good borrowers will face “adverse selection” problem from the market; on the other hand, it will lure bad borrowers to reject the “moral crisis” of the normal compliance. Thus, if the banks “general” fail to complete the credit check that careless lender prone to occur or some banks contact with “specific” enterprises are poor management will led to bad borrowers exist frequently. However, the “careless lending” or “bad borrowers” make banks operating inefficiencies, so that good borrowers can improve bank efficiency? That is main purpose and motivation of our investigation. We use Battese and Coelli (1995) stochastic frontier analysis (SFA) to investigate 38 domestic banks from1998 to 2011, a stage at the same time estimated the cost function and the inefficiency model, the inefficiency of the variables include: good borrowers and bad borrowers, the NPL ratio, coverage ratio, growth rate of money, and so on. The main source of profit of domestic banks is lending business, in the end what is the main reason of reduction in bank operating efficiency? “careless lender?” or “bad borrowers?” Through this study we want to obtain a conclusion and to give bank's credit recommendations.