本研究利用聯立方程式模型(Simultaneous Equation Models),以2004年至2008年間台灣公開上市公司為樣本,探討公司股權結構、董事會規模與董事會組成對公司經營績效之影響,實證結果顯示董事會規模越高,股權結構越低;股權結構與董事會組成越高,董事會規模越低;股權結構與董事會規模越高,董事會組成越低。上述研究結果顯示,若忽略公司治理機制間之替代關係,僅以普通最小平方法(Ordinary Least Squares, OLS)進行實證時,可能導致錯誤結論。當使用OLS時,我們發現董事會規模與績效呈現顯著正向影響,內部董事比例與績效呈現顯著正向影響,控制股東所有權與績效呈現顯著負向影響。但在兩階段最小平方法(Two-stage Least Squares, 2SLS)的實證結果中,董事會規模與績效呈現顯著負向影響,內部董事比例與績效呈現不顯著,控制股東所有權與績效呈現顯著負向影響。為增加實證結果的穩健性,另外以ROA及ROE作為績效的衡量,其測試結果與Tobin’s Q大致呈現一致性結果,並無重大差異。
This article examines the interrelations among ownership structure, board size, board composition and firm performance in a sample of listed companies in Taiwan for the period from 2004 to 2008. Using two-stage least squares (2SLS) regressions, we present evidence of interdependencies between board composition and board size. These findings suggest that cross-sectional Ordinary Least Square (OLS) regressions of performance on a single governance mechanism may be misleading. The results from OLS regressions indicate a significantly positive relationship between firm performance and board size or board composition, but a significantly negative relationship between performance and ownership structure. However, when the simultaneous equations framework is applied, we find a significantly negative relationship between performance and board size or ownership structure but no significant result for board composition. To enhance the robustness of results, ROA and ROE are both adopted as alternative performance measures and consistent results are found as that with Tobin’s Q.