The measurement of corporate portfolio strategy: analysis of the content validity of related diversification indexes
研究了熵指数和同心指数这两种最常用的相关多元化连续测量指标的内容效度，发现它们对组合构成特征敏感，可能不直接反映组合相关性，从而在战略研究中造成歧义。
Abstract Measures developed for the analysis of corporate diversification have become fundamental to a broad range of strategy research. This paper examines the content validity of the two most widely used continuous measures of related diversification—the related component of the entropy index and the concentric index—and raises fundamental questions about their validity as indicators of portfolio relatedness. These questions are not driven by the use of SIC data for estimation of the indexes; they involve validity problems intrinsic to the construction of the measures. The related component of entropy and the concentric index are sensitive to features of corporate portfolio composition that may not be directly linked to portfolio relatedness. These sensitivities can create important ambiguities in strategy research. Copyright © 2002 John Wiley & Sons, Ltd.