本研究採用Leuz、Nanda 與Wysocki (2003)、Myers、Myers 與Skinner (2006)、以及Tucker 與Zarowin (2006) 之盈餘平穩化行為衡量方式，以當年及過去四年之裁決性應計數變動數與扣除裁決性應計數之盈餘變動數間的相關係數捕捉企業之盈餘平穩化行為，來測試盈餘平穩化行為對於盈餘、權益帳面價值二變數的價值攸關性之影響。實證結果證實公司盈餘平穩化程度越大，其盈餘價值攸關性越高，權益帳面價值之價值攸關性越低，而且投資人對於裁決性應計數之正面評價亦越大。本研究進行之額外測試顯示，在其他條件不變之情況下，無論增加負債比率、負盈餘虛擬變數及股東權益報酬率三控制變數，以橫斷面Modified Jones Model 衡量盈餘管理行為，納入資訊電子業虛擬變數，以總資產進行平減及不同盈餘平穩化指標之各額外測試，皆不會改變原來結論。

This study examines the effect of income smoothing on the relative value-relevance of earnings and equity book value. Following Leuz et al. (2003), Myers et al. (2006), Tucker and Zarowin (2006), this study uses the current year's and past four years' observations to measure income smoothing by the negative correlation between the change in discretionary accruals and the change in pre-discretionary income. Using Ohlson (1995) model, this study finds that the more income smoothing, the more value-relevance increase of earnings; in contrast, the more value-relevance loss of equity book value. Furthermore, this paper finds that the more income smoothing, the more investors' positive reactions to the discretionary accruals. These results are robust to using cross-sectional modified Jones model to proxy the discretionary accruals, to controlling for debt ratio, negative earnings, return on equity, electronic industry effect, to deflating the related variables by total assets, and to using another income smoothing measure.