Bjuggren, P.-O. (2016). Marginal q revisited. Applied Economics, 48(1), 52-58. DOI: 10.1080/00036846.2015.1073842

Abstract: Two measures of firm investment behaviour used in the empirical research are Tobin’s q (average q) and marginal q. The marginal q is a more recently introduced measure than Tobin’s q and is not as well known. This article aims to demonstrate the advantages of using marginal q as a performance measure and is a response to an earlier critical article (Berglund, 2011) claiming an elusiveness bias. The pro arguments made in response are that the claimed elusiveness is not a problem. Furthermore, many of the evaluation problems inherent in the empirical use of Tobin’s q, like estimation of replacement cost of assets, can be avoided. From a pure theoretical standpoint, it has long been recognized that marginal q is superior to an average measure of investment behaviour such as Tobin’s q.