存貨與裁決性應計數之估計

Inventory and the Estimates of Discretionary Accruals

李啟華(Chi-Hua Li)

指導教授 ： 王泰昌

國立臺灣大學/管理學院/會計學研究所/博士(2008年)

https://doi.org/10.6342/NTU.2008.00776

摘要

本研究於Jones model (Jones 1991, Dechow et al. 1995) 及績效配對模型(Kothari et al. 2005)的基礎上，探討存貨具未來性的資訊內涵，是否影響裁決性應計數的估計模式。Chan et al. (2006)及Thomas and Zhang (2002)皆發現應計數與未來股價報酬呈負相關的原因(Sloan 1996)，主要來自存貨項目，代表存貨具有不同於其他應計項目之資訊內涵。藉由放寬Dechow et al. (1998)的模型假設，察覺存貨變動除了與當期銷貨變動相關外，也受銷貨收入函數的隨機過程及經理人存貨決策的影響。而經理人的決策依過去存貨與銷貨的資訊及對未來的銷貨預期而定，故不能僅以當期銷貨變動估計正常的存貨變動。因為存貨反映過去、現在及未來資訊，本研究依此估計一個包括過去、現在及未來資訊的存貨變動控制項(NorΔInv)，加入Jones model中，改善僅以當期銷貨變動估計非裁決性應計數的不足處。研究的模擬結果指出，存貨變動控制項(NorΔInv)可減少裁決性應計數的估計誤差，提升盈餘管理研究結果的可信度。
本研究另以現金增資的實際事件，測試Jones model與本研究模型，用於實際資料的差異。將樣本依銷貨與存貨變動方向，分成正向組別與反向組別，正向組別的結果與全部樣本一致地指出，現金增資公司有向上管理盈餘的現象。但是在反向組別?堙A二種模型的結果都無顯著的結果。而將反向組別的微小變動值刪除，增加模型估計的誤差後，Jones model裁決性應計數之結果指出，現金增資公司有顯著的向下盈餘管理行為，而本研究模型之裁決性應計數結果，依然呈不顯著的情況。這個結果說明Jones model在銷貨成長樣本中，會做出向下管理盈餘的誤判，而存貨變動控制項能改善Jones model的估計偏誤。

關鍵字

裁決性應計數 ； 存貨 ； 盈餘管理

並列摘要

This study examines the role of inventory on estimates of discretionary accruals. Chan et al. (2006) and Thomas and Zhang (2002) indicate that the negative relation between accruals and future abnormal returns pointed out by Sloan (1996) is due mainly to changes in inventory, so there is more information in changes in inventory than in other accrual items. This paper modifies the model of Dechow et al. (1998) to show that changes in inventory do not just depend on changes in sales, but both on generation processes of sales and firms’ inventory policies. As mentioned above, it is not appropriate to only using current changes in sales to estimate normal changes in inventory, one of nondiscretionary accrual components. However, few studies investigate the effect of inventory on discretionary accruals. To overcome this shortcoming, this study proposed inventory control variables, (NorΔInv), that captures the past, current, and future information in inventory. After adding the control variable to Jones, modified-Jones and performance-matched models, this study examines the specification and the power of tests based on the discretionary accrual measures with the inventory control variables and compares with tests using original discretionary accrual measures. Besides, the study also examines the effect of inventory control variables on discretionary accruals by SEO event. The evidence of SEO event indicates that Jones model esimates discretionary accruals with bias and the inventory control variables could mitigate the bias. The results suggest that the inventory control variables can improve the specification and power of test of discretionary accrual measures and enhance the reliability of inferences from earnings management research.

並列關鍵字

Discretionary accruals ； Inventory ； Earnings management

參考文獻

Thomas, J., and H. Zhang. 2002. Inventory changes and future returns. Review of Accounting Studies 7: 163-187.

Aharony, J., C. Lin, and M. Loeb. 1993. Initial public offerings, accounting choices, and earnings management. Contemporary Accounting Research 10: 61-81.

Ali, A., L. Hwang, and M. A. Trombley. 2000. Accruals and future stock returns: Tests of the naïve investor hypothesis. Journal of Accounting, Auditing, and Finance 15: 161-181.

Ball, R., and L. Shivakumar. 2008. Earnings quality at initial public offerings. Journal of Accounting and Economcis, forthcoming.

Barth, M. E., D. P. Cram, and K. K. Nelson. 2001. Accruals and the prediction of future cash flows. The Accounting Review 76: 27-58.