The role of weighting in corporate governance ratings

This methodological paper highlights the differences and the resulting implications from the application of the three most commonly applied weighting index methods to measuring corporate governance quality at an aggregate level: the Dichotomous; the partial compliance (PC) unweighted; and the Experts’ methods. In particular, first, we demonstrate how each method is applied and provide the details needed for readers to replicate each method. Second, we employ these methods on a sample of companies and compare the corresponding scores by testing their differences statistically. Third, as an indicative example of the potential implications arising from the use of these measures, we test whether the relation between market value and corporate governance levels differs, depending on the method applied. We find that the three methods produce significantly different overall and relative (i.e., ranking order) scores and, consequently, the relation between market value and corporate governance levels differs, depending on the method applied. Thus, we contribute to the corporate governance literature by showing that weighting in corporate governance indices matters and we recommend simultaneous application of at least two methods (i.e., the PC unweighted and the Experts’ methods) for deriving robust findings.