本研究旨在探討事務所市占率成長幅度與公開發行公司之會計監督委員會(PCAOB)檢查報告揭露之審計缺陷之關聯。本研究以機器學習作為研究方式，分析大量PCAOB檢查報告中之審計缺陷類型。實證結果顯示，市占率成長幅度在該年排名第90百分位數以上之小型事務所，其發生審計缺陷之機率較排名第89百分位數以下之事務所高1.4251倍，換言之，市占率成長幅度過快，將導致「成長陣痛」，使審計缺陷發生之機率增加，研究結果符合預期。本研究亦發現，市占率成長幅度越高，越可能發生「與財務報表層級相關」以及「與GAAP相關」之二類型審計缺陷。本研究之貢獻在於運用新興機器學習演算提供PCAOB檢查報告之主題分析，研究結果或能闡明事務所市占率成長幅度對PCAOB檢查報告揭露之審計缺陷之影響。

The purpose of this study is to explore the association between the growth rate of the audit firm's market share and the audit deficiencies revealed in the Public Company Accounting Oversight Board inspection reports. This study uses machine learning as a research method to analyze the audit defect types in a large number of PCAOB inspection reports. The empirical results show that small audit firms whose market share growth rate is above the 90th percentile in that year are 1.4251 times more likely to have audit deficiencies than those ranked below the 89th percentile. Excessive growth in market share will lead to "growing pains" and increase the probability of audit deficiencies. The research results are in line with expectations. This study also found that the higher the market share growth rate, the more likely two types of audit deficiencies, "related to the financial statement level" and "related to GAAP", will occur. The contribution of this study is to provide a thematic analysis of PCAOB inspection reports using emerging machine learning algorithms, and the findings may shed light on the impact of an audit firm’s market share growth on audit deficiencies revealed by the PCAOB.

壹、緒論 1
一、研究動機與目的 1
二、研究問題 3
貳、文獻探討 5
一、PCAOB檢查程序 5
二、機器學習 7
三、事務所之市占率成長幅度 9
參、研究假說建立 11
肆、研究方法 12
一、實證模型及變數衡量 12
二、資料來源與樣本選取 18
三、資料處理及分析方法 21
伍、實證研究結果 23
一、敘述性統計分析 23
二、相關係數分析 28
三、迴歸結果分析 31
四、額外測試 36
陸、結論與限制 40
一、研究結論 40
二、研究限制 42
柒、附錄 43
捌、參考文獻 48

一、中文文獻
徐佳揚，2021，利用深度學習預測審計失敗--以台灣為例，台灣大學會計研究所碩士論文。
二、英文文獻
Abbott, L. J., K. A. Gunny, and T. C. Zhang. 2013. When the PCAOB talks, who listens? Evidence from stakeholder reaction to GAAP-deficient PCAOB inspection reports of small auditors. Auditing: A Journal of Practice & Theory 32 (2): 1-31.
Acito, A. A., C. E. Hogan, and R. D. Mergenthaler. 2018. The effects of PCAOB inspections on auditor-client relationships. The Accounting Review 93 (2): 1-35.
Aobdia, D. 2018. The impact of the PCAOB individual engagement inspection process—Preliminary evidence. The Accounting Review 93 (4): 53-80.
Aobdia, D., and N. Shroff. 2017. Regulatory oversight and auditor market share. Journal of Accounting and Economics 63 (2-3): 262-287.
Aziz, S., and M. Dowling. 2019. Machine learning and AI for risk management. Disrupting Finance: 33-50.
Barron, O., J. Pratt, and J. D. Stice. 2001. Misstatement direction, litigation risk, and planned audit investment. Journal of Accounting Research 39 (3): 449-462.
Bauwhede, H. V., and M. Willekens. 2004. Evidence on (the lack of) audit-quality differentiation in the private client segment of the Belgian audit market. European Accounting Review 13 (3): 501-522.
Beasley, M. S., J. V. Carcello, and D. R. Hermanson. 2001. Top 10 audit deficiencies. Journal of Accountancy 19 (1): 63.
Bell, T. B., M. Causholli, and W. R. Knechel. 2015. Audit firm tenure, non‐audit services, and internal assessments of audit quality. Journal of Accounting Research 53 (3): 461-509.
Beneish, M. D., M. B. Billings, and L. D. Hodder. 2008. Internal control weaknesses and information uncertainty. The Accounting Review 83 (3): 665-703.
Bigus, J., and R. C. Zimmermann. 2008. Non‐audit fees, market leaders and concentration in the German audit market: A descriptive analysis. International Journal of Auditing 12 (3): 159-179.
Bills, K. L., Q. T. Swanquist, and R. L. Whited. 2016. Growing pains: Audit quality and office growth. Contemporary Accounting Research 33 (1): 288-313.
Boone, J. P., I. K. Khurana, and K. Raman. 2015. Did the 2007 PCAOB disciplinary order against Deloitte impose actual costs on the firm or improve its audit quality? The Accounting Review 90 (2): 405-441.
Brown, N. C., R. M. Crowley, and W. B. Elliott. 2020. What are you saying? Using topic to detect financial misreporting. Journal of Accounting Research 58 (1): 237-291.
Carcello, J. V., C. Hollingsworth, and S. A. Mastrolia. 2011. The effect of PCAOB inspections on Big 4 audit quality. Research in Accounting Regulation 23 (2): 85-96.
Cecchini, M., H. Aytug, G. J. Koehler, and P. Pathak. 2010. Detecting management fraud in public companies. Management Science 56 (7): 1146-1160.
Chan, K. C., B. Farrell, and P. Lee. 2008. Earnings management of firms reporting material internal control weaknesses under Section 404 of the Sarbanes-Oxley Act. Auditing: A Journal of Practice & Theory 27 (2): 161-179.
Chang, C. J., Y. Luo, and L. Zhou. 2017. Audit deficiency and auditor workload: evidence from PCAOB triennially inspected firms. Review of Accounting and Finance 16 (4): 478-496.
Chen, Y.-S., J. Hsu, M.-T. Huang, and P.-S. Yang. 2013. Quality, size, and performance of audit firms. The International Journal of Business and Finance Research 7 (5): 89-105.
Coram, P., J. Ng, and D. R. Woodliff. 2004. The effect of risk of misstatement on the propensity to commit reduced audit quality acts under time budget pressure. Auditing: A Journal of Practice & Theory 23 (2): 159-167.
Davidson, R. A., and D. Neu. 1993. A note on the association between audit firm size and audit quality. Contemporary Accounting Research 9 (2): 479-488.
DeAngelo, L. E. 1981. Auditor size and audit quality. Journal of Accounting and Economics 3 (3): 183-199.
DeFond, M. L., and C. S. Lennox. 2011. The effect of SOX on small auditor exits and audit quality. Journal of Accounting and Economics 52 (1): 21-40.
Dopuch, N., R. W. Holthausen, and R. W. Leftwich. 1987. Predicting audit qualifications with financial and market variables. Accounting Review 62 (3): 431-454.
Francis, J. R. 1984. The effect of audit firm size on audit prices: A study of the Australian market. Journal of Accounting and Economics 6 (2): 133-151.
Ghosh, A., and S. Lustgarten. 2006. Pricing of initial audit engagements by large and small audit firms. Contemporary Accounting Research 23 (2): 333-368.
Gramling, A. A., J. Krishnan, and Y. Zhang. 2011. Are PCAOB-identified audit deficiencies associated with a change in reporting decisions of triennially inspected audit firms? Auditing: A Journal of Practice & Theory 30 (3): 59-79.
Gunny, K. A., and T. C. Zhang. 2013. PCAOB inspection reports and audit quality. Journal of Accounting and Public Policy 32 (2): 136-160.
Hermanson, D. R., R. W. Houston, and J. C. Rice. 2007. PCAOB inspections of smaller CPA firms: Initial evidence from inspection reports. Accounting Horizons 21 (2): 137-152.
Hoitash, R., A. Markelevich, and C. A. Barragato. 2007. Auditor fees and audit quality. Managerial Auditing Journal 22 (8): 761-786.
Houston, R. W. 1999. The effects of fee pressure and client risk on audit seniors' time budget decisions. Auditing: A Journal of Practice & Theory 18 (2): 70-86.
Hrazdil, K., J. Novak, R. Rogo, C. Wiedman, and R. Zhang. 2020. Measuring executive personality using machine‐learning algorithms: A new approach and audit fee‐based validation tests. Journal of Business Finance & Accounting 47 (3-4): 519-544.
Jones, S., D. Johnstone, and R. Wilson. 2017. Predicting corporate bankruptcy: An evaluation of alternative statistical frameworks. Journal of Business Finance & Accounting 44 (1-2): 3-34.
Khurana, I. K., N. G. Lundstrom, and K. Raman. 2021. PCAOB Inspections and the Differential Audit Quality Effect for Big 4 and Non–Big 4 US Auditors. Contemporary Accounting Research 38 (1): 376-411.
Krishnan, J., J. Krishnan, and H. Song. 2017. PCAOB international inspections and audit quality. The Accounting Review 92 (5): 143-166.
Lamoreaux, P. T. 2016. Does PCAOB inspection access improve audit quality? An examination of foreign firms listed in the United States. Journal of Accounting and Economics 61 (2-3): 313-337.
Lobo, G. J., and Y. Zhao. 2013. Relation between audit effort and financial report misstatements: Evidence from quarterly and annual restatements. The Accounting Review 88 (4): 1385-1412.
Lopez, D. M., and G. F. Peters. 2012. The effect of workload compression on audit quality. Auditing: A Journal of Practice & Theory 31 (4): 139-165.
Manry, D. L., T. J. Mock, and J. L. Turner. 2008. Does increased audit partner tenure reduce audit quality? Journal of Accounting, Auditing & Finance 23 (4): 553-572.
Mascha, M. F., M. A. Lamboy-Ruiz, and D. J. Janvrin. 2018. PCAOB inspections: An analysis of entity-level and application-level control audit deficiencies. International Journal of Accounting Information Systems 30: 19-39.
Menon, K., and D. D. Williams. 1991. Auditor credibility and initial public offerings. Accounting Review 66: 313-332.
Neal, T. L., and R. R. Riley Jr. 2004. Auditor industry specialist research design. Auditing: A Journal of Practice & Theory 23 (2): 169-177.
Reynolds, J. K., and J. R. Francis. 2000. Does size matter? The influence of large clients on office-level auditor reporting decisions. Journal of Accounting and Economics 30 (3): 375-400.
Roybark, H. M. 2007. An analysis of audit deficiencies based on PCAOB inspection reports issued during 2005. Journal of Accounting, Ethics, and Public Policy 6 (2): 125–154.
Shroff, N. 2020. Real effects of PCAOB international inspections. The Accounting Review 95 (5): 399-433.
Simunic, D. A., and M. T. Stein. 1996. Impact of litigation risk on audit pricing: A review of the economics and the evidence. Auditing: A Journal of Practice & Theory 15: 119-134.
Stewart, E. G. 2012. PCAOB Inspections and Audit Quality: Evidence from Cross-Listed Securities. Working paper, Florida Atlantic University.
Sun, J., and G. Liu. 2011. Client‐specific litigation risk and audit quality differentiation. Managerial Auditing Journal 26 (4): 300-316.
Xiao, T., C. Geng, and C. Yuan. 2020. How audit effort affects audit quality: An audit process and audit output perspective. China Journal of Accounting Research 13 (1): 109-127.