本研究的目的，在於檢視購併案產生後，企業的報酬是否會受到平均數復歸（Mean reversion）的影響，而逐漸回復到產業的平均報酬。並且分析主併公司與被併公司佔雙方總資產比例的高低差異，所受到的不同影響程度。 本次研究的樣本採用1987～2006年中的美國電子電機產業共77件購併案，並依照主併公司佔雙方總資產的比例不同，分成為兩個群集。將兩群集做比較分析。實證結果顯示，兩個群集均有顯著的平均數復歸現象。而主併佔雙方總資產比例較高的群集，在購併第一年即有顯著的優於產業平均報酬，而主併與被併資產相近的群集，則是於第四年開始才有顯著的績效改善。根據實證結果，我們做出以下的結論： 1.企業的報酬具有平均數復歸的特性，表現優良的公司會被他人學習，而使整體產業平均報酬逐漸提升，漸漸蠶食原先與產業平均之間的差距；相反的，表現不佳的公司亦透過學習，逐漸改善自己的績效，也使的整體產業平均報酬上升，最後雙方都將趨向產業的平均水準。 2.當研究者要分析企業遭受偶發性事件（如購併）的影響時，應當考慮平均數復歸的所帶來的效果。如果忽略了平均數復歸所帶來的效果，將會對事件產生的影響給予錯誤的解讀。 3.面對購併績效的研究時，必須移除平均數復歸的負面效果，如此才得以正確估計購併後的績效表現。且此時主併公司資產佔雙方資產比例較高者，於購併第一年就有明顯的績效改善的效果，而雙方資產相近者，則在購併成立後第四年開始才有較佳的績效表現。 / The purpose of this research is to look over the return of enterprise can receive influence from mean reversion on post-merger performance. And it analyzes the degree of influence on acquirer companies with different proportion in total assets of both acquirer and target companies. The sample of this research adopts 77 cases of electronic and electrical equipment industry of U.S.A. in 1987- 200, take according to the proportion of total assets of acquirer company in both total assets of acquirer and target company, divide into two clusters. Make comparative analysis of these two clusters. According to the empirical results, we make the following conclusions: 1.The return of enterprises has characteristic of mean reversion. Both well performed companies and worse performed companies will move toward the whole industry's average return. 2.As the researcher wants to analyze the influence of enterprises suffered from the sporadic incident (such as M&A), they should consider the phenomenon of mean reversion. Take off the negative result of the mean reversion in order to estimate correctly for the exactly performance after M&A. 3.The acquirer companies which total assets have a higher proportion in both acquirer and target companies, will have superior to industry average return apparently in first year, and the acquirer companies which total assets close to the target companies, will have apparent improvement in performances until the fourth year.

整體而言，會計盈餘提供財務報表使用者有關於企業獲利能力之相關資訊。然而，由於會計盈餘同時包含了雜訊 (noises) 與偏差 (biases)，因而影響到會計盈餘對公司獲利能力評價的正確性。因此，過去的會計文獻發展出不同的盈餘管理估計模型 (如: Healy 1985; DeAngelo 1986; Friedlan 1994; DeFond and Jiambalvo 1994 以及Dechow, Sloan and Sweeney 1995)，以嘗試去除這些雜訊與偏差。然而，究竟哪一個估計模型能夠提供最為純淨之非裁量性淨利 (nondiscretionary income) 的衡量指標，則並無定論。在效率市場 (market efficiency) 的假說下，本研究透過本益比 (P/E ratio) 的平均數復歸 (mean-reverting) 現象來評比五種盈餘管理估計模型。由於過去的文獻同時發現盈餘成長率與風險係數均會影響本益比的高低，因此，本研究同時將這兩個變數納入考量。 　　實證結果發現，依照上述五種盈餘管理估計模型所估計之本益比皆有平均數復歸的現象。其中Friedlan (1994) 模型在全體樣本與控制盈餘成長率之後，其本益比平均數復歸現象均較其他模型為快；次佳之盈餘管理估計模型為DeFond and Jiambalvo (1994) 與Dechow et al. (1995) 兩模型；最差的則為 Healy (1985) 模型。 / Overall speaking, accounting earnings provide financial statement users with useful information about a firm's profitability. However, because of the biases and noises included in the accounting earnings, the accuracy and reliability of accounting earnings to the evaluation of a firm's profitability may be adversely influenced. In light of this, prior earnings management studies have developed various estimation models of nondiscretionary income (e.g., Healy 1985; DeAngelo 1986; Friedlan 1994; DeFond and Jiambalvo 1994; Dechow, Sloan & Sweeney 1995) with an attempt to remove the biases and noises embedded in the accounting earnings. Nonetheless, there is no consistent empirical evidence about the relative performance of these estimation models. Assuming market efficiency, the main purpose of this study is to utilize the mean-reverting phenomenon of P/E ratios to evaluate the relative performance of these models. Since prior studies have found that earnings growth rate and risk coefficient may affect the magnitude of P/E ratios, we also control for these two variables in our analyses. 　　The empirical results reveal several findings. First, P/E ratios calculated using different earnings management estimation models exhibit the mean-reverting phenomenon. Second, the Friedlan (1994) model has the best performance among all models when we use the overall sample and three subsamples grouped based on the earnings growth rate. In addition, the DeFond and Jiambalvo (1994) and Dechow, Sloan & Sweeney (1995) models perform moderately. Finally, the Healy (1985) model shows the worst performance.

本論文是二篇探討與股票價格平均數復歸現象有關的實證文章。在第一篇文章中，我們將探討由於廠商特質所產生資金供需雙方訊息的非對稱，而引發的流動性限制對廠商股票價格行為的潛在影響；在第二篇文章中，我們研究的課題是在漲跌幅限制下，交易量與股票報酬自我相關的關係。 第一篇文章主要在探討由於廠商特質所產生資金供需雙方訊息的非對稱，而引發的流動性限制對廠商股票價格行為的影響。我們利用五個廠商特質－所有權結構、集團企業成員、上市時間、公司規模與現金股利的發放，定義面臨流動性限制的廠商，並使用變異數比率衡量股票價格平均數復歸的現象，由於小樣本的問題，我們將利用拔靴法檢定假說：廠商的流動性限制會強化其股票價格平均數復歸的行為。我們的實證結果並不一致，所有權結構、公司規模和集團企業成員的分組實證結果支持我們的假說，流動性限制會強化平均數復歸的行為；而上市時間與現金股利發放的分組實證結果並不支持我們的假說。 在第二篇文章中，我們使用與Campbell et. al. (1993)相同的實證模型，討論在漲跌幅限制下，交易量與股票日報酬自我相關的關係。由於漲跌幅限制的存在，當股票價格觸及漲跌幅上下限時，即停止交易，而使得真正的股票價格無法觀察到，因而未實現之需求或供給將會傳遞至下一個交易日，將使傳統OLS或其衍生方法的估計產生偏誤，而使用Chou和Chib (1995)與Chou (1995)所提的Gibbs抽樣法則可以成功地克服這些困難。所以，本文將應用Chou和Chib (1995)與Chou (1995)的Gibbs抽樣法來衡量台灣股票市場交易量對股票日報酬自我相關係數的影響，以避免漲跌幅限制的影響。本文採用台灣證交所編製的綜合股價指數所採樣的二十四家公司為樣本，利用日資料進行實證分析，實證結果支持「交易量效果」的存在。且在實證過程中，發現台灣股票市場股票日報酬的正自我相關有可能是漲跌幅限制的存在而造成的。

思及當前捉襟見肘的財政窘境，無可避免地，債台高築的臺灣實陷入飲鴆止渴般以債養債之無限迴圈中，導致政府政策效能不彰、社會福利運作生弊亦無可厚非；於『公共債務法』之財政規範下，臺灣業已瀕臨法定舉債門檻，故不論是對短期政府支出之排擠、扭曲性稅率之稽徵抑或對長期經濟成長的斲傷，皆是身為中華民國國民真正惶悚不安之所在。 職是之故，本研究係採用一納入政府財政部門及貨幣當局之擴充『實質景氣循環模型』，藉以Sidrauski（1967）所提出的貨幣效用函數為出發點，將實質餘額引進理論模型，並透過計量操作捕捉實證期間起於西元1971年第一季迄至2007年第四季之政府政策函數，過程中，我們不難發現政府購買性支出及稅率皆存在相當的持續性，且對政府未償公債餘額之高低作出某種程度的反應。亦即，若政府實施公債融通政策，俾使期初公債餘額較高之際，則本期甚或往後各期的政府支出將遭受抑制和排擠，尤有甚者，政府勢必擬以提高未來稅率以茲挹注該債務之還本付息所造成的財政缺口；是以，本研究著眼於引進公債餘額對政府支出及稅率存在反饋作用下，財政政策與貨幣政策之總體效果及各總體變數之動態調整過程的風貌。即便公債發行或賒借為政府提供一財務週轉工具以裨益財政政策保有更靈活之彈性，然據模型所產生的結果顯示，就長期而論，政府必須維持一穩定之未償公債餘額，即公債水準具備『均數復歸』性質，而該財政目標係透過削減未來政府支出、調整扭曲性稅率及鑄幣稅融通政策方得以達成預算平衡，準此，該設定將造成公債融通之減稅政策對經濟體系具有實質效果，『公債融通』管道亦『非中立性政策』，從而傳統『李嘉圖等值定理』於本模型中無法成立。 就政策面層次而言，本研究試圖放寬『反饋法則』與政策係數之設定，以檢視透過不同程度之政府支出、稅率甚至貨幣供給途徑的改變來平衡因增加公債發行所造成的財政赤字，對經濟體系之長短期效果有何迥異處；是文亦藉由衝擊反應函數分別探討於政府支出增加、減稅措施及貨幣擴張之下，政策的傳遞機制與各總體變數之動態性質，顯然地，就高債務比率前提下，當政府戮力於刺激景氣而欲積極實施立竿見影的總體經濟政策之際，卻常因狃於急效而欲速不達，非但政策效果有限，亦可能使體系落入更為不景氣的田地，從而，財政惡化不啻為經濟危機的導火線也就不言而喻。再者，貨幣政策對體系之實質變數具有一定程度的作用，是故，本模型於短期內無法一窺『貨幣中立性』之堂奧，唯長期始得以復見。總括言之，政府亟須奉『健全財政』為圭臬，擬定政策時更得戒慎恐懼，並適切權衡利弊得失，以茲裨益有更具信心的經濟表現。 此外，本研究亦透過『效準』實驗以評估模型『配適度』之良窳，即便於反覆疊代法下，該模擬表現係瑕瑜互見而不盡完美，卻也大抵符合景氣循環之『典型化特徵』；然就實質景氣循環模型所為人詬病之勞動市場一隅而論，引進公債之反饋法則下的財政政策操作，無疑地改善了傳統工時與工資率動輒高度正相關之本質，從而獲致相對較低之理論相關係數，亦朝實證資料所呈現工時與工資率存在幾近零相關甚或低度負相關之表徵更邁進一大步。 / With current financial difficulties beyond government capability, it is inevitable that the already deep-in-debt Taiwan opted for momentary relief by paying debt through debt financing and ended up in an infinite loop, causing spiral-down performances in government policies and faulty operations of social welfare instruments. Taiwan has been on the verge of reaching the statutory upper limit of debt financing according to “The Public Debt Act” regulations and all nationals are becoming anxious about such impacts as crowding out of short-run government spending, levying of distorting taxes, and damages on long-run economic growth. To better understand the debt’s impacts, this research uses the “Real Business Cycle Model” extended by taking government treasury agency and monetary institution into account. Starting with Money In Utility Function (MIUF) as proposed by Sidrauski (1967) to introduce real money balance into the theoretical model and, in the process of econometric manipulation, to detect empirical governmental policy functions in the period between the first quarter, 1971 and the fourth quarter, 2007, it is not hard to discover that there are considerable persistence in both government purchases and tax rates, with manifestation of certain degree of responses to the total amount of outstanding bonds the government has yet to pay. In other words, a governmental bond financing policy designed to render high initial bonds outstanding tends to cause suppression and crowding out of government spending in current and even later periods. Furthermore, the government is bound to plan on raising taxes in the future in order to cut financial deficit gap caused by paying back the principles and interests of the debt. Therefore, this study focuses on presenting the macroeconomic effects of fiscal policies and monetary policies, as well as the dynamic adjustment processes of macroeconomic variables based on the impact of feedback effect of bonds outstanding on government spending and tax rates. Even thought public bonds issuance or debt financing serves as a governmental fiscal instrument for financial turnover to ensure flexibility of fiscal policies, our model shows that the government should, from a long-run perspective, maintain a stable amount of bonds outstanding. Put in a different way, the level of bonds outstanding shows “mean-reverting” characteristics which rely on future government spending cut, distorting tax adjustment and seigniorage financing policy to achieve balance of budget. As a result, such setup would cause the bond-financing backed tax deduction policies to create practical effects on economies and, as the bond financing instruments are “Non-Neutrality” policies, would render the “Ricardian Equivalence Theorem” invalid in our model. In the policy aspect, this study tries to relax both “feedback rules” and setup of policy parameters for investigating the differences between long-run and short-run effects on the economy by different degrees of changes in government spending, tax rates and even money supply channels which are used to balance the fiscal deficit caused by increased bond issuance. This article also studies, through the impulse response function, the policy propagation mechanism and the dynamics of key macroeconomic variables under the situation of government spending increase, tax deduction and monetary expansion. It is obvious that the government, in the case of high debt ratios and when making all endeavors to spur economy by implementing macroeconomic policies aimed for instant results, is accustomed to seeking quick fixes only to achieve very limited effects, sometimes even to drive the economy into further recession. It is therefore evident that fiscal degradation could lead to economic disaster. Moreover, as the monetary policies have certain degrees of influence on real variables of the economy, this model will not be able to clearly analyze the “neutrality of money” in such a short period of time. The effect will only reveal in the long run. In summary, the government should keep “sound finance” as the highest guiding principle and be extremely cautious in formulating policies in order to weigh all pros and cons discreetly, thus help to achieve a benefiting economic performance that generates more confidence. Furthermore, this study assesses “goodness of fit” of the model through a “calibration” experiment. Although the simulation results show, under recursive method, intermingled good and poor occasions that are beyond satisfaction, they generally agree with the “typical characteristics” of business cycles. However, in the aspect of long-criticized labor market of the real business cycle model, the fiscal policy operation under feedback rules with introduction of public debts for sure has greatly improved on the conventional intrinsic property of high correlation between labor hours and real wage rates, by delivering a relatively low theoretical correlation coefficient, which is a big step towards the empirical results of almost zero or even weakly negative correlation between labor hours and real wage rates.