為應對行業日益激烈的競爭，會計師事務所往往採取不同的經營策略以取得更好的經營績效，進而提高市場競爭力。據此，本文探討會計師事務所業務多元化與客戶集中度對會計師事務所利潤率之影響。且進一步分析客戶集中度對業務多元化與事務所利潤率之調節效果。本研究以2002年至2018年台灣會計師事務所服務業為研究對象，並採用熵指標(Entropy)與赫芬達指數(Hirshman-Herfindahl Index)分別衡量業務多元化與客戶集中度以進行本文之實證研究。本研究主要有三項實證結果，其一為業務多元化與會計師事務所利潤率間具顯著之非線性關聯性，其二為客戶集中度對會計師事務所利潤率具負向之影響，其三為客戶集中度對業務多元化與事務所利潤率之關係具調節作用。前述三項實證結果皆會因會計師事務所的組織型態及規模大小之而有不同之結果。本文之研究結果或可有助於會計師事務所於發展業務多元化策略時可納入客戶業別集中度為考量之依據，以俾利未來管理階層達到該經營策略之參考，尤其是，客戶集中度與會計師事務所利潤率關聯性以及客戶集中度對業務多元化與事務所利潤率調節影響之實證結果填補了會計師產業之文獻缺口。

In response to the increasing competition in the industry, accounting firms often adopt different business strategies to achieve better operating performance, thereby enhancing market competitiveness. Based on this, this article explores the impact of accounting firms’ business diversification and client industry concentration on the profitability of accounting firms. And further analyze the moderating effect of customer concentration on the business. This study takes the service industry of Taiwanese accounting firms from 2002 to 2018 as the research object. Entropy and Hirshman-Herfindahl Index are used to measure business diversification and customer concentration respectively for the empirical research of this article. This study has three main empirical results. One is the significant non-linear correlation between business diversification and the profitability of accounting firms, the other is the negative impact of customer concentration on the profitability of accounting firms, and the third is Customer concentration has a moderating effect on the relationship between business diversification and firm profitability. The aforementioned three empirical results will all have different results depending on the organizational type and size of the accounting firm.  The research results in this article may help accounting firms to consider customer industry concentration when developing business diversification strategies, so as to facilitate future management to achieve the business strategy as a reference, in particular, customer concentration  The empirical results of the correlation with the accounting firm's profit rate and the influence of customer concentration on the business diversification and firm's profit rate adjustment fill the gaps in the accounting industry's literature.

第一章 緒論
第一節 研究背景……………………………………………………...1
第二節 研究動機……………………………………………………...1
第三節 研究目的……………………………………………………...3
第四節 研究流程……………………………………………………...4
第二章 文獻回顧
第一節 多元化經營之意義、種類及衡量………………….6
第二節 多元化經營對企業績效影響之研究………………8
第三節 產業專業化之意義、種類及衡量.........16
第四節 產業專業化對企業財務績效之影響……………..19
第五節 文獻評述…………………………………………………….20
第三章 研究設計
第一節 研究架構…………………………………………………….23
第二節 研究假說…………………………………………………….23
第三節 研究變數…………………………………………………….25
第四節 估計模型…………………………………………………….34
第五節 資料來源…………………………………………………….36
第四章 實證結果
第一節 敘述統計分析……………………………………………...38
第二節 相關係數分析……………………………………………...42
第三節 迴歸分析結果……………………………………………...50
第四節 敏感度分析…………………………………………………54
第五章 研究結論、意涵與未來研究建議
第一節 研究結論…………………………………………………….79
第二節 研究意涵…………………………………………………….80
第三節 研究限制與未來研究建議  ………………………...81
參考文獻
 
表目錄
表2.1.1多元化經營對企業財務績效正向影響之文獻彙總         9
表2.2.2多元化經營對企業財務績效負向影響之文獻彙總        11
表2.2.3多元化經營對企業財務績效非線性影響之文獻彙總      11
表2.2.4多元化經營對企業財務績效未具影響之文獻彙總        12
表2.2.5多元化經營對企業非財務績效具正向影響之文獻彙總    13
表2.2.6多元化經營對企業非財務績效具負向影響之文獻彙總    13
表2.2.7多元化經營對企業價值具正向影響之文獻彙總          14
表2.2.8多元化經營對企業價值具負向影響之文獻彙總          15
表2.2.9多元化經營與企業價值間具非線性影響之文獻彙總      15
表2.4.1產業專業化對企業具正向影響之文獻彙總              19
表2.4.2產業專業化對企業特定變數具負向影響之文獻彙總      20
表3-3-1本研究各變數操作性定義彙總表                      29
表3-5-1各年度不同規模之原始事務所樣本點                  37
表3-5-2各年度不同規模之處理過事務所樣本點                37
表4-1-1敘述統計:全體樣本                               38
表4-1-2敘述統計:單獨開業型會計師事務所                   39
表4-1-3敘述統計:聯合開業型會計師事務所                   39
表4-1-4敘述統計:大型會計師事務所                         40
表4-1-5敘述統計:小型會計師事務所                         41
表4-2-1相關係數分析:全體樣本                             42
表4-2-2相關係數分析:單獨開業型會計師事務所               44
表4-2-3相關係數分析:聯合開業型會計師事務所               45
表4-2-4相關係數分析:大型會計師事務所                     47
表4-2-5相關係數分析:小型會計師事務所                     48
表4-3-1業務多元化對會計師事務所利潤率之影響              50
表4-3-2業務多元化對會計師事務所利潤率之非線性影響        51
表4-3-3客戶業別集中度對事務所利潤率之影響                52
表4-3-4客戶集中度對業務多元化與事務所利潤率之調節影響    53
表4-3-5不同群體客戶集中度調節效果彙總                    54
表4-4-1業務多元化對事務所利潤率之影響                    55
表4-4-2業務多元化對事務所利潤率之非線性影響              56
表4-4-3業務多元化對每位合夥人之淨利影響                  57
表4-4-4業務多元化對每位合夥人淨利之非線性影響            58
表4-4-5業務多元化對每位合夥人收入之影響                  59
表4-4-6業務多元化對每位合夥人收入之非線性影響            60
表4-4-7客戶業別集中度對事務所利潤率之影響                61
表4-4-8客戶業別集中度對每位合夥人淨利之影響              62
表4-4-9客戶業別集中度對每位合夥人收入之影響              63
表4-4-10客戶業別集中度(前六大)對事務所利潤率之影響        64
表4-4-11客戶業別集中度(前七大)對事務所利潤率之影響        65
表4-4-12客戶集中度對業務多元化與事務所利潤率影響之調節   66
表4-4-13客戶集中度對業務多元化與事務所利潤率影響之調節   67
表4-4-14客戶集中度對業務多元化與每位合夥人淨利影響之調節 68
表4-4-15客戶集中度對業務多元化與每位合夥人收入影響之調節 69
表4-4-16客戶集中度(前六大)對業務多元化與事務所利潤率影響之
調節                                             70
表4-4-17客戶集中度(前七大)對業務多元化與事務所利潤率影響之
調節                                             71
表4-4-18業務多元化對事務所利潤率影響(2002-2008)           72
表4-4-19業務多元化對事務所利潤率之非線性影響(2002-2008)   73
表4-4-20客戶集中度對事務所利潤率之影響(2002-2008)         74
表4-4-21客戶集中度對業務多元化與事務所利潤率影響之調節   74
表4-4-22業務多元化對會計師事務所利潤率之影響(2009-2018)   75
表4-4-23業務多元化對事務所利潤率之非線性影響(2009-2018)   76
表4-4-24客戶集中度對會計師事務所利潤率之影響(2009-2018)   77
表4-4-25客戶集中度對業務多元化與事務所利潤率影響之調節   78
 
圖目錄
圖1-1-1研究流程圖                                5
圖3-1-1研究架構圖                                23
圖3-3-2民國103-105年我國會計師事務所全年各項收入
-按收入項目別分                                   30
圖3-3-3民國105-107年我國會計師事務所全年各項收入
-按收入項目別分                                   31
圖3-3-4民國105年我國會計師事務所全年執行業務收入分配比
-按委託人之業別分                                 32
圖3-3-5民國107年我國會計師事務所全年執行業務收入分配比
-按委託人之業別分                                 33

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