隨著中國大陸經濟的高度成長，不動產市場也隨之發展。在貸款利率及不動產相關稅負長期偏低之下，住宅產品的投資需求不斷上升，使得房價一路高漲。房屋價格的增幅過大、增速過高，已經超出了合理的範圍。截至2010年，中國大陸推出一系列以抑制房價為主要目的的宏觀調控政策，許多重點城市也陸續推出以“限購令”為主要內容的地方性政策來調控不動產市場。由於中國大陸地幅遼闊，各地的不動產市場因受各種因素影響而發展各異，因此挑選了北京、上海、廣州三個頗具代表性的重點城市作為研究對象。本文應用年租金與加權平均資本成本（WACC）還原基本價值，以其與市場價格間的差距作為泡沫程度的估計，計算出這三個城市2007年至2012年間不動產價格泡沫程度。藉由這三個城市的不動產市場泡沫狀況，運用共整合分析檢視中國城市不動產價格泡沫的影響因素，并以Granger因果關係檢定探討三地不動產價格泡沫與各因素之領先落後關係。 實證結果顯示，人均可支配收入和金融機構各項信貸總額對不動產價格泡沫具有正向影響，不動產價格泡沫則對其本身具有負向影響，而抵押貸款利率與不動產價格泡沫先是正相關而後轉為負相關的關係。而根據Granger因果關係檢定結果，北京不動產價格泡沫落後於金融機構各項貸款總額，而上海不動產價格泡沫領先於人均可支配收入，廣州不動產價格泡沫則落後於人均可支配收入、抵押貸款利率與金融機構各項貸款總額。 / With the rapid economic development in China, the real estate market has been undergoing a great boom. The low interest and tax rates are very favorable for the continuously increasing house demands, and thus resulting in higher housing prices. And the extremely rapidly increasing housing prices are not reasonable. Until 2010, Chinese government had published a series of national housing regulatory decisions to address the over-heating real estate market. And the restrictions on house purchase have been put into practice in some major cities. Given that China has a vast territory with large variety, the impact of these regulations on the local real estate markets of the cities can hardly be determined. Therefore, we study here the real estate market in Beijing, Shanghai and Guangzhou, three of the most representative major cities in China. This study evaluates the housing bubbles situations in these cities from 2007 to 2012 by comparing fundamental values with market prices. The fundamental value of real estate can be calculated by annual rents and WACC. Based on the evaluated housing bubbles situations, this study then applies Cointegration analysis to further explore the factors that may contribute to China’s housing bubbles. In addition, Granger causality test is employed to examine the lead/lag relationship between housing bubbles and the variables. The empirical result shows that per-capita disposable incomes and total loans of financial institutions are positively related to China’s housing bubbles. And the housing bubbles in these three cities are negatively related to themselves. In addition, the impact of interest rates on housing bubbles is positive and later turns negative with respect to the magnitude of increasing rates. According to the results of Granger causality tests, Beijing’s housing bubbles are Granger caused by total loans while property bubbles in Shanghai lead personal incomes. Furthermore, housing bubbles in Guangzhou are Granger caused by personal disposable incomes, interest rates and total loans.

過去研究說明具產業專長之會計師仍能在客戶財務資訊不完整情況下，利用其行業特定知識與較高技術能力執行完善的審計工作(Thibodeau 2003; Moroney 2007; Hammersley 2006)。本論文定義資訊不確定性為客戶之財務資訊無法幫助預測公司的價值(Zhang 2006; Autore et al. 2009)。本論文推論若公司的財務報表具有不確定性會需要聘請產業專長會計師以減緩資訊不確定性的程度，並進一步研究具資訊不確定性公司若由非產業專長更換為產業專長會計師是否能提升其審計品質。由於審計工作目的在於提供資訊品質的確認(Dye 1993; Knechel et al. 2008)，審計人員會依據審計客戶的環境，設計和執行適當的審計計劃以減輕資訊不確定性情況。本論文以會計師角度建立一資訊不確定性架構，進一步將資訊不確定性分為基本價值波動不確定性與資訊品質不確定性，並推論產業專長會計師比較能在資訊品質不確定性中發揮其價值。本論文分為兩部分：第一部分檢驗資訊不確定性是否會影響產業專長會計師之選任，第二部分則檢測具資訊不確定性之審計客戶若選擇產業專長會計師之後，其審計品質是否會提升。 / Previous studies establish that a specialist auditor has more industry-specific knowledge and higher technological capability that can pertinently benefit situations in which client financial information is incomplete (Thibodeau 2003; Moroney 2007; Hammersley 2006). In this paper, we define information uncertainty as the ambiguity with respect to the implications of new information concerning a firm’s value (Zhang 2006; Autore et al. 2009). Because some financial statements present information in uncertain terms, we infer that companies whose financial statements provide uncertain information demand specialist auditors to alleviate the extent of information uncertainty. We further examine the improvements on audit quality made by those companies under information uncertainty which chose to switch from non-specialist auditors to specialist ones. As an assurance of information quality (Dye 1993; Knechel et al. 2008), an auditor, based on his knowledge of the auditee and its environment, will alleviate the uncertainty level of the auditee’s financial information through designing and executing an appropriate audit plan. We build a framework of information uncertainty and develop comprehensive measurements of information uncertainty from the auditor’s point of view. Moreover, this study disentangles the information uncertainty effects into fundamental volatility uncertainty and information quality uncertainty, and proposes that specialist auditors manifest their merits more under information quality uncertainty than under fundamental volatility uncertainty. In the first part of this study, we examine the auditors chosen by companies whose financial statements are characterized by information uncertainty. Previous studies on auditor choice address many reasons why companies switch their auditors (Lennox 2000; Carcello and Neal 2003; Blouin et al. 2007). Information uncertainty makes stakeholders lower their reliance upon company financials and even downgrade the filers, triggering negative stock price reactions (Merton 1987; Beneish et al. 2005; Beneish et al. 2008; Hammersley et al. 2008). Based on prior research, we can infer that a company under information uncertainty chooses to hire a specialist auditor to signal the credibility of the financial statements and improve market perception. We hypothesize that companies suffering uncertainty demand specialist auditors to alleviate their information uncertainty. The auditor’s information role is to ensure the reliability of financial information, and a specialist auditor is equipped with superior audit knowledge and technology. Therefore, we further infer that a company whose specific information uncertainty is attributable to information quality issues (rather than fundamental volatility issues) is more inclined to choose a specialist auditor. This is because a specialist auditor improves the credibility of financial information instead of being involved with the client’s business decisions. We use an auditor switching sample of U.S. companies from 2001-2009 to examine whether the information uncertainty is an issue of auditor choice or not. Consistent with our conjecture, companies under information uncertainty prefer to hire specialist auditors. Evidence partially supports that relative to companies under fundamental volatility uncertainty, companies suffering information quality uncertainty are more inclined to choose specialist auditors. In the second part of this study, we find evidence for the economic consequences of upgrading switches to a specialist auditor when the company is experiencing information uncertainty. After the Sarbanes-Oxley Act (hereafter, SOX), many companies began to take the cost-effect issue into consideration; they ultimately decided to go private (Zhang 2006; Engel et al. 2007) in order to avoid the high-cost of Section 404 or switch to a non-Big N audit firm (Calderon et al. 2007). There's no such thing as free lunch; the specialist auditor usually has greater ability and concomitant higher charges (Craswell et al. 1995; DeFond et al. 2000; Francis et al. 2005; Cahan et al. 2008). It is natural to question whether every company needs to engage specialist auditors if it has to pay high audit fees. In this paper, we attempt to determine in which circumstances specialist auditors can make a significant difference in improving audit quality. We investigate the relationship between auditor specialization and audit quality in an information uncertainty setting using an auditor switching sample taken from 2001 to 2009 in the United States. We examine ex post facto whether (1) specialist auditors improve audit quality more than their non-specialist counterparts; and (2) specialist auditors manifest their merits more under information quality uncertainty than the fundamental volatility uncertainty. Since the value of auditor industry specialization is reflected by the perceived and actual audit quality (Balsam et al. 2003; Nagy 2005), we examine both earnings response coefficient (ERC) and accruals quality to proxy audit quality (DAC). In both models, the audit quality of companies that suffer fundamental volatility uncertainty along with comprehensive uncertainty is not enhanced substantially following upgrade switching to a specialist auditor. We find strong empirical results that demonstrate companies under information quality uncertainty show significant improvements in audit quality after switching to specialist auditors. However, specialist auditors are significantly more capable of mitigating the information quality uncertainty than the fundamental volatility uncertainty. That is, auditor specialization is a critical solution when companies encounter information quality uncertainty.