本文旨在研究應計項目前期估計錯誤數的揭露是否能為投資人提供具決策攸關性的資訊，並檢視經理人投機性財務報導的行為是否受到此項揭露所影響。本文的研究動機係著眼於會計資訊攸關性與可靠性之取捨。會計學者認為，要求公司揭露應計項目前期估計錯誤數可增加會計估計的可靠性且不犧牲盈餘數字的攸關性。然而現有文獻並未對此一見解提出相關證據。 本文使用美國財務會計準則委員會第45號解釋函所要求的產品保證負債揭露來檢視事後揭露前期應計項目估計錯誤的影響。主要發現為：投資人對於過去應計項目估計錯誤波動較大的公司（亦即較不精確的過去盈餘數字），會給予未預期盈餘較低的評價，顯示投資人認為前期估計錯誤數的揭露具決策攸關性，而此差異評價之情形僅出現於投資人取得估計精確性的資料之後。此外，當期產品保證負債估計錯誤數與當期盈餘操縱的發生呈正向相關，且此一相關性於第45號解釋函發佈後變得較不顯著，顯示事後揭露前期應計項目估計錯誤數有助於減少透過產品保證負債估計所進行的盈餘管理。

This paper investigates whether ex post disclosures of prior-period estimation errors in accounting accruals provide value-relevant information to investors and whether such disclosures discourage opportunistic reporting by managers. Several researchers argue that by requiring managers to disclose past estimation errors, the financial reporting system can increase the reliability of estimates and at the same time preserve the relevance of reported earnings. There is, however, litter empirical evidence on the validity of this argument. Using the mandated disclosures of prior-period estimation errors in product warranty liabilities required by FIN 45, I find that investors attach a smaller valuation multiple to unexpected earnings for firm-quarters with more variable past estimation errors in product warranty liabilities (i.e., less precise past earnings), suggesting that investors consider ex post disclosures of past estimation errors decision-relevant. The differential valuation multiples are observed only after but not before the information about past estimation precision becomes available to the market. Moreover, there is an association between current period estimation errors in product warranty liabilities and proxies for the occurrence of earnings management in the current period. Such an association becomes less pronounced after the implementation of FIN 45, implying that the ex post disclosures of prior-period estimation errors curb accrual management through product warranty liabilities.