The risk, however, is that such controls also capture economic factors - including policy changes - which have been a source of growing inequalities. This is particularly the case for policies associated with skill-biased technological change (SBTC): empirically, SBTC has been usually proxied by time trends and found to be a significant driver of higher wage dispersion (Braconier and Ruiz-Valenzuela, 2014; OECD, 2011b, Katz and Murphy, 1994; Acemoglu and Autor, 2012). This implies that the empirical results in this paper could fail to identify some policy effects on household incomes, i.e. those that are channelled via SBTC. The majority of growth-oriented empirical studies on structural reforms have focused on the two main proximate determinants of GDP per capita - labour productivity and employment - or on a number of intermediate drivers, which include investment in physical capital, trade, R&D and multifactor productivity.