本研究以「變異數成份分析法」探討1996至2008年台灣服務業企業績效之重要影響因素。實證模型分別具體探討在ROA、Tobin's Q、EVA三個績效衡量指標下，產業效果、公司效果、年效果以及產業和年交互影響效果對於企業績效的相對重要程度。實證研究發現以EVA為績效衡量指標的解釋力最高，達77.79%，穩定的產業效果以及年浮動的產業效果分別解釋37.84%和21.75%的總變異，顯示產業結構面要素相對於公司管理及策略面要素對台灣服務業企業績效的影響力較高。另外，我們亦發現2001年之前，年浮動產業效果對企業績效的影響力相當大，而2001年之後則為穩定的產業效果對企業績效的影響力較大，此結果說明台灣服務業的發展結構於2000年後已漸趨於穩定。本研究發現不論從整個研究期間抑或是分別從不同研究期間的結果來看，皆顯示影響台灣服務業企業績效最直接的原因即產業結構因素，故服務業企業應投入正確的產業以獲得良好的經營績效。

Implementing a variance decomposition analysis for firm performance measures (including EVA, Tobin's Q, and ROA) in Taiwan services sector from 1986 to 2008, the purpose of this paper is to examine the relative importance of industry, corporate, year, and transient industry effects on firm performance. Further, it is of interest whether distinct performance measures produce different analysis results. The evidence shows that the EVA explains 77.79% of the total variance in firm performance, which is much larger than other applied measures. The stable and transient industry effects on EVA are 37.84% and 21.75%, respectively, which suggests that structural characteristics of industry are more important for firm performance than corporate management strategies. The transient industry effects are much larger than other effects in the first period (1996-2001) but stable industry effects are more important for performance in the second period (2002-2008). This may indicate that the industry structure of Taiwan services sector has turned toward the stable development gradually. Finally, structural features of industry have a significant impact on firm performance in Taiwan's services sector.