公司治理、資訊透明度與公司信用評等關係之實證研究

The Relationship among Corporate Governance, Information Transparency, and Credit Rating

謝明娟(Ming-Chuan Hsieh)

指導教授 ： 王維康

元智大學/管理學院/會計學系/碩士(2009年)

摘要

本文探討公司治理、資訊透明度與公司信用評等關係之實證研究。過去許多研究均將資訊揭露程度視為信用評等的重要衡量變數，將資訊透明度與其他相關變數一起加入模型中探討，而衡量資訊透明度之研究中，常包含相關公司治理變數，卻鮮有學者研究資訊透明度與其他公司治理變數是否存在內生性問題，因此，本文欲探討信用評等與資訊透明度間各公司治理變數影響兩者之關係，並以兩階段最小平方法試圖解決二者之內生性問題。
本文以2005-2007年台灣公開上市公司資料為樣本，並採聯立方程式探討公司治理與信用評等是否相關、公司治理與資訊透明度之關係及資訊透明度與信用評等之關係。研究結果發現，當公司治理愈好信用評等與資訊透明度愈好，且資訊透明度對於信用評等有正面影響，但信用評等對資訊透明度並無顯著關係。而經由聯立方程式之兩階段最小平方法(2SLS)分析消除內生性問題後，實證結果發現獨立董監事席次比例並非直接影響信用評等，並發現在原OLS中彼此具顯著關係的信用評等與資訊透明度，在2SLS之下，僅資訊透明度對信用評等有顯著正相關，而信用評等並無顯著影響資訊透明度。在比較OLS與2SLS實證結果之差異後，發現在探討資訊透明度與信用評等之研究變數時，若以OLS解釋其實證結果，將能產生其變數間之顯著相關是因未知的第三因素所造成之偏誤。

關鍵字

公司治理 ； 信用評等 ； 資訊透明度

並列摘要

We investigate the relationship among corporate governance, information transparency, and credit rating in this study. Much of the prior literature regards information transparency, which is included in the model together with other related variables, as an important variable for measuring credit rating. Related corporate governance variables are often included in the studies for measuring information transparency; however, few scholars investigate whether there is an endogenous problem between information transparency and other corporate governance variables. For this reason, we discuss the relationship how corporate governance variables affect credit rating and information transparency. We attempt to solve the endogenous problem between credit rating and information transparency by using the simultaneous equations.
Our sample period is selected to be from 2005 to 2007, including 1,694 firm-year observations with Taiwan public corporations. We use the two-stage least square method (2SLS) of the simultaneous equations to investigate the following objectives: (1) whether there is positive relationship between corporate governance and credit rating; (2) the relationship between corporate governance and information transparency; and (3) the relationship between information transparency and credit rating. Our analysis yields several key findings. We find that the better the corporate governance, the better the transparency. Information transparency has a positive effect on credit rating, but credit rating has no significant relationship with information transparency. After the 2SLS analysis eliminating endogenous problem, we find that the proportion of independent directors on the board doesn’t significantly affect credit rating. In OLS analysis, credit rating and information transparency significantly affect each other. However, through 2SLS analysis, only information transparency has a significantly positive effect on credit rating, and credit rating has no significant relationship with information transparency. After comparing the difference between OLS and 2SLS, when investigating the measuring variables of information transparency and credit rating, we find that, if we use OLS to explain our empirical results, it might lead to bias.

並列關鍵字

Corporate Governance ； Credit Rating ； Information Transparency

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