重大非審計服務與審計品質－－來自內部控制專案審查之證據

The Association between Substantial Non-Audit Services and Audit Quality: Evidence from Special Audit of Internal

提供非審計服務是否一定會對會計師的獨立性或審計品質構成威脅，長久以來一直存有爭議。本研究旨在從會計師抑制盈餘管理的角度，探討當會計師接受客戶審計委任又額外執行內部控制專案審查此一重大非審計服務時，財務利益的誘因是否將減損當年度的審計品質。實證結果發現，經由傾向分數配對法（propensity score matching method）控制非審計服務內生性特徵後，在博達案前，會計師同時執行內部控制專案審查時，其審計品質相對變得較差，即使改以Heckman（1979）兩階段估計法控制非審計服務內生性情況下，實證結論仍然維持不變，支持準租利益威脅獨立性的論點。

Whether non-audit services can impair auditor independence and audit quality has been controversial for a long time. By utilizing abnormal accruals as an observable proxy for audit quality, the purpose of this study is to examine whether audit quality is impaired when auditors provide audit services and simultaneously conduct substantial non-audit services like special audit of internal control system. Using propensity score matching method discussed by Lennox et al. (2012) to control non-audit services self-selection bias, the empirical results show that auditors compromise their audit quality if they provide the special audit of internal control system to their clients concurrently before Procomp event. These results are still robust when the two-stage Heckman (1979) approachis adopted. That supports DeAngelo's (1981a) quasi-rents arguments.