更換會計師及審計品質變化對財務資訊品質之影響

Abstract

本研究以台灣上市櫃公司，於2001年至2005年間更換會計師事務所的30家公司，觀察其更換前後審計品質之改變，並同時從資訊觀點以及衡量觀點的角度，比較前後三年間財務資訊品質之差異，探討更換會計師以及審計品質的變化，對於財務資訊品質之影響。 審計品質衡量的結果，審計品質上升的公司包括由非大型事務所更換會大型事務所，或是同類型事務所間更換，但更換後的事務所在規模或是產業專業性上有所提升的公司。 資訊觀點的研究結果顯示，公司在更換會計師後，股票市場的表現不如更換會計師前的表現，顯示經營狀況有變差的跡象，然而所報導的盈餘資訊，卻呈現表現良好的訊息，尤其在換會計師後審計品質變差的公司特別明顯，同時其盈餘資訊價值佔過去一年淨資訊價值的比例，也較更換前或是審計品質提升的公司低，顯示更換至審計品質較差的會計師事務所，其財務資訊品質也會下降。 衡量觀點的研究結果顯示，公司在更換會計師後，若審計品質下降，則所報導的財務資訊，包括股東權益帳面價值以及超額盈餘，用來評估股票價值的影響力皆下降，顯示公司在更換至審計品質較差的事務所時，其所報導的財務資訊有被高估的可能性，故使得資訊品質下降。

This study examines the impact on the financial information quality from both information perspective and measurement perspective for 30 publicly traded Taiwan companies undergoing auditor switches during year 2001 to 2005. The audit quality change between the predecessor and the successor audit firm is also examined. The audit quality is measured as increase if the company changed the auditor from non-big firms to big firms or if the company changed the auditor between the same type firms but the successor auditor either is greater in size or has better expertise in auditing the industry in which the company is involved. From the information perspective, the stock market performance after the change was worse than the performance before the change, but the earnings numbers reported after the changes were inclined to reveal good news to investors, especially for those companies hiring an audit firm with lower audit quality. The ratio of earnings information value to net information value for the companies with audit firm’s audit quality decreased was also lower than that before the switch or that for the companies with audit firm’s audit quality increased. From the measurement perspective, the effectiveness of the financial information, such as equity book value and abnormal earning, in the Residual Income Model is decreased after the company switched to the auditor whose audit quality is lower. This reveals that the reported financial information might be overestimated and therefore the information quality is lower.