一家公司引進獨立董事是否有助於改善財務績效與強化公司治理在理論與實證上一直沒有一致性的結論，既有實證文獻大多缺乏考慮公司引進獨立董事的樣本自我選擇(Self-Selection)可能性，致使評估獨立董事對公司績效影響時產生估計上的自我選擇估計偏誤。本文應用Rubin (1973, 1977)以及Rosenbaum and Rubin (1983, 1985a,b)的配對(Matching)與傾向分數配對(Propensity Score Matching)，考量既有研究中公司引進獨立董事的決定因素，根據這些變數是否相近為依據，進行樣本篩選與配對，使得引進獨立董事之公司與未引進獨立董事之公司在這些變數上接近於近似，改善樣本的自我選擇偏誤問題。本文根據2001~2011年非金融業之上市公司資料進行分析發現，在樣本配對前，平均來說，引進獨立董事的公司其獲利能力較高，經理人薪酬亦相對較高；但在樣本配對後，引進獨立董事之公司的獲利能力優勢變得不明顯，經理人薪酬卻仍然相對較高。因此本文的結論是透過樣本配對以降低樣本的自我選擇估計偏誤後，引進獨立董事並無法增進公司績效，在抑制公司經理人薪酬上的效果也相對有限。本文的基本結果在另一種矯正樣本選擇偏誤的估計方法即Heckman (1979)兩階段估計法下並未出現明顯的改變。

Based on data of listed-companies on Taiwan Stock Exchange (TWSE) through 2001~2011, this paper examines whether board independence has effects on executives compensation and corporate performance. Existing studies lacked of considering self-selection of board independence in evaluating the effects of board independence on economic consequence. This may incur estimation bias because systematic factors which determine firm’s pursuing board independence also have influences on economic consequence. While Heckman (1979)’s two-step estimation addresses sample selection duo to unobservable variable, this paper employs propensity score matching (PSM) from Rosenbaum and Rubin (1983, 1985a,b) to address sample selection duo to observable variable, and forms two groups of samples, namely, firms with independent director and firms without independent director but share similar observable characteristics with the former. Empirical evidence from regression estimation shows divergent outcomes under before-matching versus after-matching samples. Before matching, greater degree of board independence is associated with higher profitability and higher level of total/average executives compensation. After matching, outperformance as well as overpay on executives compensation of firm with greater board independence is vanished. After controlling selection bias duo to observables versus unobservables, our evidence concludes that greater board independence is uncorrelated with greater corporate performance and executive compensation overpay.

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